/* ============================================================
   DIGITAL LAB — Design System v2.0
   Premium dark glassmorphism with subject accent colors
   ============================================================ */

/* ── CSS Variables ─────────────────────────────────────────── */
:root {
  /* Base */
  --bg-primary: #030407;
  --bg-secondary: #060810;
  --bg-card: #0b1020;
  --bg-card-hover: #111827;
  --bg-glass: rgba(6, 8, 16, 0.8);
  --border-glass: rgba(255, 255, 255, 0.05);
  --border-glass-hover: rgba(255, 255, 255, 0.09);

  /* Text */
  --text-primary: #f0f2f5;
  --text-secondary: #8b95a8;
  --text-muted: #525c6e;

  /* Subject Accents */
  --physics-primary: #3b82f6;
  --physics-glow: rgba(59, 130, 246, 0.35);
  --physics-bg: rgba(59, 130, 246, 0.1);
  --chemistry-primary: #a855f7;
  --chemistry-glow: rgba(168, 85, 247, 0.35);
  --chemistry-bg: rgba(168, 85, 247, 0.1);
  --biology-primary: #22c55e;
  --biology-glow: rgba(34, 197, 94, 0.35);
  --biology-bg: rgba(34, 197, 94, 0.1);

  --prelab-glow-1: #00f0ff;
  --prelab-glow-2: #7a5cff;
  --prelab-glow-3: #ff00ea;
  --success-color: #10b981;

  /* UI */
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 22px;
  --radius-xl: 30px;

  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 8px 32px rgba(0,0,0,0.5);
  --shadow-lg: 0 20px 60px rgba(0,0,0,0.7);

  --transition-fast: 0.18s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);

  /* Spacing */
  --section-gap: 56px;
  --content-max-width: 1240px;
}

/* ── Light Theme Overrides ──────────────────────────────────── */
[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-hover: rgba(255, 255, 255, 1);
  --bg-glass: rgba(255, 255, 255, 0.7);
  --border-glass: rgba(0, 0, 0, 0.06);
  --border-glass-hover: rgba(0, 0, 0, 0.12);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;

  --shadow-sm: 0 2px 8px rgba(0,0,0,0.04);
  --shadow-md: 0 8px 32px rgba(0,0,0,0.08);
  --shadow-lg: 0 20px 60px rgba(0,0,0,0.12);

  /* Light Mode Specific Accents (High Contrast) */
  --physics-primary: #2563eb;
  --physics-glow: rgba(37, 99, 235, 0.2);
  --physics-bg: rgba(37, 99, 235, 0.08);

  --chemistry-primary: #7c3aed;
  --chemistry-glow: rgba(124, 58, 237, 0.2);
  --chemistry-bg: rgba(124, 58, 237, 0.08);

  --biology-primary: #16a34a;
  --biology-glow: rgba(22, 163, 74, 0.2);
  --biology-bg: rgba(22, 163, 74, 0.08);

  --prelab-glow-1: #0ea5e9;
  --prelab-glow-2: #8b5cf6;
  --prelab-glow-3: #d946ef;
}

/* ── Light theme overrides for floating navbar ───────────── */
[data-theme="light"] .fnav {
  background: rgba(245, 247, 250, 0.82);
  border-color: rgba(0, 0, 0, 0.08);
  box-shadow: 0 4px 32px rgba(0, 0, 0, 0.08), 0 1px 0 rgba(0,0,0,0.06) inset;
}
[data-theme="light"] .fnav::before {
  background: rgba(255, 255, 255, 0.6);
}
[data-theme="light"] .fnav-item {
  color: #475569;
}
[data-theme="light"] .fnav-item:hover {
  color: #0f172a;
  background: rgba(0, 0, 0, 0.05);
}
[data-theme="light"] .fnav-item--active {
  background: rgba(37, 99, 235, 0.12) !important;
  color: #2563eb !important;
  border-color: rgba(37, 99, 235, 0.25) !important;
  box-shadow: 0 0 0 1px rgba(37,99,235,0.15), 0 2px 8px rgba(37,99,235,0.12) !important;
}
[data-theme="light"] .fnav-brand-name { color: #0f172a; }
[data-theme="light"] .fnav-brand-sub { color: #94a3b8; }
[data-theme="light"] .fnav-brand-icon {
  background: rgba(37, 99, 235, 0.1);
  color: #2563eb;
  box-shadow: none;
}
[data-theme="light"] .fnav-action-btn {
  color: #475569;
  background: rgba(0,0,0,0.04);
  border-color: rgba(0,0,0,0.08);
}
[data-theme="light"] .fnav-action-btn:hover {
  background: rgba(0,0,0,0.08);
  color: #0f172a;
}
[data-theme="light"] .fnav-panel {
  background: rgba(255, 255, 255, 0.98);
  border-color: rgba(0,0,0,0.08);
  box-shadow: 0 12px 40px rgba(0,0,0,0.12), 0 0 0 1px rgba(0,0,0,0.04);
}
[data-theme="light"] .fnav-panel-item { color: #475569; }
[data-theme="light"] .fnav-panel-item:hover { background: rgba(0,0,0,0.04); color: #0f172a; }
[data-theme="light"] .fnav-mobile {
  background: rgba(245, 247, 250, 0.98);
  border-top-color: rgba(0,0,0,0.06);
}
[data-theme="light"] .fnav-mobile-item { color: #475569; }
[data-theme="light"] .fnav-mobile-item:hover { background: rgba(0,0,0,0.04); color: #0f172a; }
[data-theme="light"] .fnav-mobile-item--active { color: #2563eb; background: rgba(37,99,235,0.08); }
[data-theme="light"] .fnav-mobile-divider { color: #94a3b8; border-color: rgba(0,0,0,0.06); }
[data-theme="light"] .fnav-profile-chip {
  background: rgba(0,0,0,0.04);
  border-color: rgba(0,0,0,0.08);
  color: #0f172a;
}
[data-theme="light"] .fnav-profile-chip:hover {
  background: rgba(37,99,235,0.08);
  border-color: rgba(37,99,235,0.25);
}
[data-theme="light"] .fnav-login-btn {
  background: rgba(37,99,235,0.1);
  color: #2563eb;
  border-color: rgba(37,99,235,0.25);
}
[data-theme="light"] .fnav-login-btn:hover {
  background: rgba(37,99,235,0.18);
}
[data-theme="light"] .lang-dropdown {
  background: rgba(255, 255, 255, 0.98);
  box-shadow: 0 16px 48px rgba(0,0,0,0.15), 0 0 0 1px rgba(0,0,0,0.05);
}
[data-theme="light"] .lang-option:hover {
  background: rgba(0, 0, 0, 0.04);
}
[data-theme="light"] .back-btn {
  background: rgba(0,0,0,0.04);
}
[data-theme="light"] .back-btn:hover {
  background: rgba(0,0,0,0.08);
}
[data-theme="light"] .nav-time {
  background: rgba(0,0,0,0.04);
}

[data-theme="light"] .lab-record-toggle:hover {
  background: rgba(0,0,0,0.03);
}

[data-theme="light"] .lab-record-item {
  background: rgba(0,0,0,0.02);
}

[data-theme="light"] .subject-tag {
  background: rgba(0,0,0,0.04);
}

[data-theme="light"] .orb { opacity: 0.12; }

[data-theme="light"] ::-webkit-scrollbar-thumb { background: rgba(0,0,0,0.15); }
[data-theme="light"] ::-webkit-scrollbar-thumb:hover { background: rgba(0,0,0,0.25); }

/* ── Theme Toggle Button ────────────────────────────────────── */
.theme-toggle-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 17px;
  cursor: pointer;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}
.theme-toggle-btn:hover {
  background: rgba(255,255,255,0.12);
  border-color: var(--border-glass-hover);
  color: var(--text-primary);
  transform: scale(1.08);
}
[data-theme="light"] .theme-toggle-btn {
  background: rgba(0,0,0,0.04);
}
[data-theme="light"] .theme-toggle-btn:hover {
  background: rgba(0,0,0,0.08);
}

/* ── Smooth theme transition ────────────────────────────────── */
*, *::before, *::after {
  transition-property: background-color, border-color, color, box-shadow;
  transition-duration: 0.25s;
  transition-timing-function: ease;
}

/* ── Reset ─────────────────────────────────────────────────── */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  line-height: 1.65;
  font-size: 15px;
  letter-spacing: -0.01em;
}

/* ── Scrollbar ─────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.1); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: rgba(255,255,255,0.2); }

/* ============================================================
   FLOATING CAPSULE NAVBAR — fnav
   Premium glass, mouse-tracking light, liquid active pill
   ============================================================ */

/* ── Wrapper (floating capsule) ─────────────────────────── */
.fnav {
  position: fixed;
  top: 14px;
  left: 50%;
  transform: translateX(-50%);
  width: calc(100% - 32px);
  max-width: 1080px;
  z-index: 1000;
  border-radius: 18px;
  background: rgba(6, 8, 18, 0.72);
  backdrop-filter: blur(24px) saturate(1.8);
  -webkit-backdrop-filter: blur(24px) saturate(1.8);
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow:
    0 8px 32px rgba(0, 0, 0, 0.55),
    0 1px 0 rgba(255, 255, 255, 0.06) inset,
    0 0 0 0.5px rgba(255, 255, 255, 0.04);
  transition: box-shadow 0.35s ease, background 0.35s ease;
  overflow: visible;
}

/* Subtle top highlight stripe */
.fnav::before {
  content: '';
  position: absolute;
  top: 0; left: 16px; right: 16px;
  height: 1px;
  border-radius: 0 0 2px 2px;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.12) 30%, rgba(255,255,255,0.18) 50%, rgba(255,255,255,0.12) 70%, transparent);
  pointer-events: none;
}

/* Scrolled: tighter shadow */
.fnav--scrolled {
  box-shadow:
    0 12px 48px rgba(0, 0, 0, 0.7),
    0 1px 0 rgba(255, 255, 255, 0.08) inset,
    0 0 0 1px rgba(59, 130, 246, 0.06);
}

/* ── Mouse-following inner light orb ────────────────────── */
.fnav-light-orb {
  position: absolute;
  top: -80px;
  left: -80px;
  width: 160px;
  height: 160px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(59, 130, 246, 0.12) 0%, transparent 70%);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.25s ease;
  transform: translate(0, 0);
  will-change: transform, opacity;
  z-index: 0;
}

/* ── Inner flex row ─────────────────────────────────────── */
.fnav-inner {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 56px;
  padding: 0 14px;
}

/* ── Brand ──────────────────────────────────────────────── */
.fnav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  flex-shrink: 0;
  transition: opacity var(--transition-fast);
  margin-right: 8px;
}
.fnav-brand:hover { opacity: 0.82; }

.fnav-brand-icon {
  width: 32px;
  height: 32px;
  border-radius: 10px;
  background: rgba(59, 130, 246, 0.15);
  border: 1px solid rgba(59, 130, 246, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #60a5fa;
  box-shadow: 0 0 12px rgba(59, 130, 246, 0.2);
  transition: box-shadow var(--transition-fast), transform var(--transition-fast);
  flex-shrink: 0;
}
.fnav-brand-icon svg { width: 15px; height: 15px; }
.fnav-brand:hover .fnav-brand-icon {
  box-shadow: 0 0 20px rgba(59, 130, 246, 0.35);
  transform: scale(1.06) rotate(-3deg);
}

.fnav-brand-text { display: flex; flex-direction: column; line-height: 1; }
.fnav-brand-name {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}
.fnav-brand-sub {
  font-size: 10.5px;
  color: var(--text-muted);
  font-weight: 400;
  letter-spacing: 0.3px;
  margin-top: 1px;
}

/* ── Nav links row ──────────────────────────────────────── */
.fnav-links {
  display: flex;
  align-items: center;
  gap: 2px;
  flex: 1;
  margin: 0 4px;
}

/* ── Single nav item (link or button) ───────────────────── */
.fnav-item {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 6px 13px;
  border-radius: 10px;
  font-size: 13.5px;
  font-weight: 550;
  font-family: 'Inter', sans-serif;
  color: rgba(255, 255, 255, 0.55);
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  border: 1px solid transparent;
  background: transparent;
  transition:
    color 0.18s ease,
    background 0.18s ease,
    border-color 0.18s ease,
    box-shadow 0.18s ease;
  position: relative;
  letter-spacing: -0.01em;
  user-select: none;
}
.fnav-item:hover {
  color: rgba(255, 255, 255, 0.9);
  background: rgba(255, 255, 255, 0.06);
}

/* Active: liquid blue glass pill */
.fnav-item--active {
  color: #93c5fd !important;
  background: rgba(59, 130, 246, 0.14) !important;
  border-color: rgba(59, 130, 246, 0.28) !important;
  box-shadow:
    0 0 0 1px rgba(59, 130, 246, 0.15),
    0 2px 12px rgba(59, 130, 246, 0.18),
    inset 0 1px 0 rgba(255,255,255,0.06) !important;
  font-weight: 600;
}
.fnav-item--active:hover {
  color: #bfdbfe !important;
  background: rgba(59, 130, 246, 0.2) !important;
}

/* Dropdown button specific reset */
.fnav-dropdown-btn {
  background: transparent;
  border: 1px solid transparent;
  font-family: inherit;
}

.fnav-caret {
  width: 10px;
  height: 10px;
  opacity: 0.5;
  transition: transform 0.18s ease, opacity 0.18s ease;
  flex-shrink: 0;
}
.fnav-dropdown--open .fnav-caret {
  transform: rotate(180deg);
  opacity: 0.8;
}

/* ── Subjects dropdown panel ────────────────────────────── */
.fnav-dropdown { position: relative; }

.fnav-panel {
  position: absolute;
  top: calc(100% + 10px);
  left: 0;
  min-width: 220px;
  padding: 6px;
  background: rgba(6, 8, 18, 0.95);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 14px;
  box-shadow:
    0 16px 48px rgba(0, 0, 0, 0.65),
    0 0 0 0.5px rgba(255,255,255,0.04),
    inset 0 1px 0 rgba(255,255,255,0.06);
  backdrop-filter: blur(28px);
  -webkit-backdrop-filter: blur(28px);
  opacity: 0;
  transform: translateY(-8px) scale(0.97);
  pointer-events: none;
  transition: opacity 0.18s ease, transform 0.18s ease;
  z-index: 2000;
}
.fnav-dropdown--open .fnav-panel {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.fnav-panel-item {
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 9px 10px;
  border-radius: 10px;
  text-decoration: none;
  color: rgba(255,255,255,0.6);
  transition: background 0.15s ease, color 0.15s ease;
  cursor: pointer;
}
.fnav-panel-item:hover {
  background: rgba(255,255,255,0.06);
  color: rgba(255,255,255,0.92);
}
.fnav-panel-item--active {
  background: rgba(59,130,246,0.12);
  color: #93c5fd;
}
.fnav-panel-item--active:hover {
  background: rgba(59,130,246,0.18);
  color: #bfdbfe;
}

.fnav-panel-item-icon {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.fnav-panel-item-icon svg { width: 14px; height: 14px; }
.fnav-panel-icon--physics {
  background: rgba(59, 130, 246, 0.15);
  color: #60a5fa;
}
.fnav-panel-icon--chemistry {
  background: rgba(168, 85, 247, 0.15);
  color: #c084fc;
}
.fnav-panel-icon--biology {
  background: rgba(34, 197, 94, 0.15);
  color: #4ade80;
}

.fnav-panel-item-body {
  display: flex;
  flex-direction: column;
  line-height: 1;
}
.fnav-panel-item-label {
  font-size: 13.5px;
  font-weight: 600;
  font-family: 'Inter', sans-serif;
  letter-spacing: -0.01em;
}
.fnav-panel-item-sub {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 2px;
  font-weight: 400;
}

/* ── Right actions area ─────────────────────────────────── */
.fnav-actions {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
  margin-left: auto;
}

/* Shared icon-style action button */
.fnav-action-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 6px 10px;
  border-radius: 9px;
  font-size: 12.5px;
  font-weight: 500;
  font-family: 'Inter', sans-serif;
  color: rgba(255,255,255,0.5);
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.07);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  flex-shrink: 0;
}
.fnav-action-btn:hover {
  color: rgba(255,255,255,0.88);
  background: rgba(255,255,255,0.09);
  border-color: rgba(255,255,255,0.13);
}

/* Sign In button */
.fnav-login-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 9px;
  font-size: 13px;
  font-weight: 600;
  font-family: 'Inter', sans-serif;
  text-decoration: none;
  color: #93c5fd;
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.24);
  transition: all var(--transition-fast);
  white-space: nowrap;
}
.fnav-login-btn:hover {
  background: rgba(59, 130, 246, 0.2);
  border-color: rgba(59, 130, 246, 0.4);
  color: #bfdbfe;
  box-shadow: 0 0 12px rgba(59, 130, 246, 0.2);
}

/* ── Premium profile chip ───────────────────────────────── */
.fnav-profile-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 10px 4px 4px;
  border-radius: 100px;
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-family: 'Inter', sans-serif;
  font-size: 13px;
  font-weight: 500;
  color: rgba(255,255,255,0.7);
  position: relative;
}
.fnav-profile-chip:hover {
  background: rgba(59, 130, 246, 0.1);
  border-color: rgba(59, 130, 246, 0.3);
  color: rgba(255,255,255,0.92);
  box-shadow: 0 0 0 1px rgba(59,130,246,0.15), 0 4px 16px rgba(59,130,246,0.12);
}

/* Blue accent ring around avatar */
.fnav-avatar-ring {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: linear-gradient(135deg, #3b82f6, #6366f1);
  padding: 2px;
  box-shadow: 0 0 0 1.5px rgba(59, 130, 246, 0.5), 0 0 10px rgba(59, 130, 246, 0.3);
  flex-shrink: 0;
}

.fnav-avatar {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  background: rgba(10, 14, 26, 0.9);
  font-family: 'Space Grotesk', sans-serif;
  font-size: 12px;
  font-weight: 700;
  color: #60a5fa;
  letter-spacing: 0;
  text-transform: uppercase;
}

.fnav-profile-name {
  max-width: 88px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.fnav-profile-caret {
  display: flex;
  align-items: center;
  opacity: 0.4;
  transition: transform 0.18s ease, opacity 0.18s ease;
}
.fnav-profile-caret svg { width: 9px; height: 9px; }
.fnav-profile-chip[aria-expanded="true"] .fnav-profile-caret {
  transform: rotate(180deg);
  opacity: 0.7;
}

/* ── Profile dropdown ───────────────────────────────────── */
.user-profile { position: relative; }

.profile-dropdown {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  min-width: 200px;
  padding: 6px;
  background: rgba(6, 8, 18, 0.96);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 14px;
  box-shadow:
    0 16px 48px rgba(0, 0, 0, 0.65),
    inset 0 1px 0 rgba(255,255,255,0.06);
  backdrop-filter: blur(28px);
  -webkit-backdrop-filter: blur(28px);
  opacity: 0;
  transform: translateY(-8px) scale(0.97);
  pointer-events: none;
  transition: opacity 0.18s ease, transform 0.18s ease;
  z-index: 2100;
}
.profile-dropdown--open,
.profile-dropdown.open {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.profile-dropdown-header {
  padding: 8px 12px 10px;
  border-bottom: 1px solid rgba(255,255,255,0.06);
  margin-bottom: 4px;
}
.profile-dropdown-label {
  display: block;
  font-size: 10.5px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 3px;
}
.profile-dropdown-email {
  font-size: 12.5px;
  color: var(--text-secondary);
  font-weight: 400;
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.profile-dropdown-item {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 9px 10px;
  border-radius: 9px;
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  font-size: 13px;
  font-weight: 500;
  font-family: 'Inter', sans-serif;
  cursor: pointer;
  border: none;
  background: transparent;
  width: 100%;
  text-align: left;
  transition: background 0.15s ease, color 0.15s ease;
}
.profile-dropdown-item:hover {
  background: rgba(255,255,255,0.06);
  color: rgba(255,255,255,0.92);
}
.profile-dropdown-item-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 6px;
  background: rgba(255,255,255,0.05);
  flex-shrink: 0;
  color: var(--text-secondary);
}
.profile-dropdown-logout { color: rgba(248, 113, 113, 0.75); }
.profile-dropdown-logout:hover {
  background: rgba(239, 68, 68, 0.1);
  color: #f87171;
}
.profile-dropdown-logout .profile-dropdown-item-icon {
  background: rgba(239, 68, 68, 0.1);
  color: #f87171;
}

/* ── Language picker (reuses existing .lang-* classes) ───── */
.lang-picker { position: relative; }

/* ── Hamburger (mobile) ─────────────────────────────────── */
.fnav-hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 4.5px;
  width: 36px;
  height: 36px;
  border-radius: 9px;
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.07);
  cursor: pointer;
  padding: 0;
  transition: background var(--transition-fast);
  flex-shrink: 0;
  margin-left: 4px;
}
.fnav-hamburger:hover { background: rgba(255,255,255,0.09); }
.fnav-hamburger span {
  display: block;
  width: 16px;
  height: 1.5px;
  background: rgba(255,255,255,0.6);
  border-radius: 2px;
  transition: transform 0.22s ease, opacity 0.22s ease;
  transform-origin: center;
}
.fnav-hamburger--open span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.fnav-hamburger--open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.fnav-hamburger--open span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ── Mobile drawer ──────────────────────────────────────── */
.fnav-mobile {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  left: 0; right: 0;
  background: rgba(6, 8, 18, 0.97);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 14px;
  padding: 8px;
  box-shadow: 0 16px 48px rgba(0,0,0,0.65);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  z-index: 999;
  opacity: 0;
  transform: translateY(-8px);
  transition: opacity 0.2s ease, transform 0.2s ease;
  pointer-events: none;
}
.fnav-mobile--open {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.fnav-mobile-inner {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.fnav-mobile-item {
  display: block;
  padding: 10px 14px;
  border-radius: 10px;
  text-decoration: none;
  color: rgba(255,255,255,0.55);
  font-size: 14px;
  font-weight: 500;
  font-family: 'Inter', sans-serif;
  transition: background 0.15s, color 0.15s;
}
.fnav-mobile-item:hover {
  background: rgba(255,255,255,0.06);
  color: rgba(255,255,255,0.9);
}
.fnav-mobile-item--active {
  background: rgba(59,130,246,0.14);
  color: #93c5fd;
  font-weight: 600;
}
.fnav-mobile-divider {
  font-size: 10.5px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  padding: 6px 14px 4px;
  border-top: 1px solid rgba(255,255,255,0.05);
  margin-top: 4px;
}

/* ── Responsive: show hamburger on small screens ─────────── */
@media (max-width: 820px) {
  .fnav-links { display: none; }
  .fnav-hamburger { display: flex; }
  .fnav-mobile { display: block; }
  .fnav { top: 10px; width: calc(100% - 20px); border-radius: 14px; }
  .fnav-inner { height: 50px; padding: 0 12px; }
  /* Hide lang picker on mobile to save space */
  .lang-picker { display: none; }
}

/* ── Breadcrumb (kept for compatibility) ────────────────── */
.nav-breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
  display: none;
}
@media (max-width: 1400px) {
  .nav-breadcrumb { display: none; }
}
.nav-breadcrumb .bc-sep { color: var(--text-muted); }
.nav-breadcrumb .bc-current { color: var(--text-primary); font-weight: 500; }

.nav-menu {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-left: auto;
  margin-right: 14px;
}

.nav-menu-link {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  padding: 7px 10px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
  white-space: nowrap;
  transition: all var(--transition-fast);
}

.nav-menu-link:hover {
  color: var(--text-primary);
  background: rgba(255,255,255,0.06);
}

.nav-menu-dropdown {
  position: relative;
}

.nav-menu-button {
  border: 0;
  background: transparent;
  font-family: inherit;
  cursor: pointer;
}

.nav-menu-panel {
  position: absolute;
  top: calc(100% + 10px);
  left: 0;
  min-width: 160px;
  padding: 8px;
  background: rgba(6, 8, 16, 0.96);
  border: 1px solid var(--border-glass-hover);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(22px);
  -webkit-backdrop-filter: blur(22px);
  opacity: 0;
  transform: translateY(-6px);
  pointer-events: none;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  z-index: 2000;
}

.nav-menu-panel-wide { min-width: 210px; }

.nav-menu-dropdown:hover .nav-menu-panel,
.nav-menu-dropdown:focus-within .nav-menu-panel {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.nav-menu-panel a {
  display: block;
  padding: 9px 10px;
  border-radius: 9px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
}

.nav-menu-panel a:hover {
  color: var(--text-primary);
  background: rgba(255,255,255,0.07);
}

[data-theme="light"] .nav-menu-panel {
  background: rgba(255,255,255,0.98);
}

.nav-time {
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px;
  color: var(--text-muted);
  padding: 4px 12px;
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-glass);
}

/* ── Language Picker ─────────────────────────────────────────── */
.nav-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.lang-picker {
  position: relative;
}

.lang-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: 'Inter', sans-serif;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}
.lang-btn:hover {
  background: rgba(255,255,255,0.09);
  border-color: var(--border-glass-hover);
}
.lang-btn.open {
  background: rgba(59,130,246,0.12);
  border-color: rgba(59,130,246,0.35);
}
.lang-caret {
  font-size: 10px;
  color: var(--text-muted);
  transition: transform var(--transition-fast);
}
.lang-btn.open .lang-caret { transform: rotate(180deg); }

.lang-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  background: rgba(6, 8, 16, 0.96);
  border: 1px solid var(--border-glass-hover);
  border-radius: var(--radius-md);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  box-shadow: 0 16px 48px rgba(0,0,0,0.6), 0 0 0 1px rgba(255,255,255,0.04);
  min-width: 190px;
  z-index: 2000;
  overflow: hidden;
  opacity: 0;
  transform: translateY(-6px) scale(0.97);
  pointer-events: none;
  transition: opacity 0.18s ease, transform 0.18s ease;
}
.lang-dropdown.open {
  opacity: 1;
  transform: translateY(0) scale(1);
  pointer-events: all;
}

.lang-dropdown-header {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  padding: 10px 14px 6px;
  border-bottom: 1px solid var(--border-glass);
}

.lang-option {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 14px;
  cursor: pointer;
  transition: background var(--transition-fast);
  border: none;
  background: transparent;
  width: 100%;
  text-align: left;
}
.lang-option:hover {
  background: rgba(255,255,255,0.05);
}
.lang-option.lang-active {
  background: rgba(59,130,246,0.12);
}
.lang-option .lang-flag { font-size: 16px; line-height: 1; }
.lang-option .lang-native {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
}
.lang-option .lang-english {
  font-size: 11px;
  color: var(--text-muted);
  margin-left: auto;
}
.lang-option.lang-active .lang-native { color: #60a5fa; }
.lang-option.lang-active .lang-english { color: rgba(96,165,250,0.6); }

/* Active language indicator dot */
.lang-option.lang-active::before {
  content: '';
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: #3b82f6;
  flex-shrink: 0;
  margin-right: -4px;
}


/* ============================================================
   MAIN CONTAINER
   ============================================================ */
.main-container {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 86px 28px 64px;
  position: relative;
  z-index: 1;
}

.view { animation: fadeInUp 0.4s ease; }
.view.hidden { display: none; }

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ============================================================
   HERO
   ============================================================ */
.hero-section {
  position: relative;
  padding: 48px 0 var(--section-gap);
}

/* Dashboard background glow removed */

.hero-content {
  position: relative;
  z-index: 2;
}

.hero-badge {
  display: inline-block;
  padding: 7px 18px;
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.2);
  border-radius: 100px;
  font-size: 13px;
  color: var(--physics-primary);
  font-weight: 500;
  margin-bottom: 24px;
  letter-spacing: 0.3px;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.hero-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(32px, 5vw, 52px);
  font-weight: 700;
  line-height: 1.08;
  margin-bottom: 20px;
  color: var(--text-primary);
  letter-spacing: -0.03em;
}

.gradient-text {
  background: linear-gradient(180deg, #ffffff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 16px;
  color: var(--text-secondary);
  max-width: 560px;
  line-height: 1.75;
  letter-spacing: 0;
}

/* ============================================================
   SECTION LABEL
   ============================================================ */
.section-label {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 24px;
  padding-left: 2px;
}

/* ============================================================
   SUBJECT CARDS
   ============================================================ */
.subject-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 20px;
  margin-bottom: var(--section-gap);
}

.subject-card {
   position: relative;
   display: block;
   text-decoration: none;
   color: inherit;
   background: var(--bg-card); 
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  padding: 28px;
  cursor: pointer;
  transition: all var(--transition-smooth);
  overflow: hidden;
}
.subject-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glass-hover);
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.subject-card-glow {
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  opacity: 0;
  transition: opacity var(--transition-smooth);
  pointer-events: none;
}
.subject-card:hover .subject-card-glow { opacity: 1; }

.subject-physics .subject-card-glow { background: radial-gradient(ellipse at 30% 30%, var(--physics-glow), transparent 60%); }
.subject-chemistry .subject-card-glow { background: radial-gradient(ellipse at 30% 30%, var(--chemistry-glow), transparent 60%); }
.subject-biology .subject-card-glow { background: radial-gradient(ellipse at 30% 30%, var(--biology-glow), transparent 60%); }

.subject-physics:hover { border-color: var(--physics-glow); }
.subject-chemistry:hover { border-color: var(--chemistry-glow); }
.subject-biology:hover { border-color: var(--biology-glow); }

.subject-icon-wrap {
  width: 56px; height: 56px;
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 18px;
  position: relative;
}
.subject-physics .subject-icon-wrap { background: var(--physics-bg); }
.subject-chemistry .subject-icon-wrap { background: var(--chemistry-bg); }
.subject-biology .subject-icon-wrap { background: var(--biology-bg); }

.subject-icon { font-size: 28px; }

.subject-info { position: relative; z-index: 1; }

.subject-name {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 23px;
  font-weight: 700;
  margin-bottom: 6px;
  letter-spacing: -0.02em;
}
.subject-physics .subject-name { color: var(--physics-primary); }
.subject-chemistry .subject-name { color: var(--chemistry-primary); }
.subject-biology .subject-name { color: var(--biology-primary); }

.subject-desc {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.5;
}

.subject-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.exp-count {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
}

.subject-arrow {
  font-size: 20px;
  color: var(--text-muted);
  transition: transform var(--transition-fast), color var(--transition-fast);
}
.subject-card:hover .subject-arrow {
  transform: translateX(4px);
}
.subject-physics:hover .subject-arrow { color: var(--physics-primary); }
.subject-chemistry:hover .subject-arrow { color: var(--chemistry-primary); }
.subject-biology:hover .subject-arrow { color: var(--biology-primary); }

.subject-tag-list {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-top: 14px;
  position: relative;
  z-index: 1;
}

.subject-tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 100px;
  font-size: 11px;
  font-weight: 500;
  border: 1px solid var(--border-glass);
  color: var(--text-secondary);
  background: rgba(255,255,255,0.03);
}

/* ============================================================
   STATS BAR
   ============================================================ */
.stats-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 36px;
  padding: 28px 32px;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.stat-num {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 22px;
  font-weight: 700;
  color: var(--text-primary);
}

.stat-label {
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.stat-divider {
  width: 1px;
  height: 32px;
  background: var(--border-glass);
}

/* ============================================================
   SUBJECT HEADER (list view)
   ============================================================ */
.subject-header {
  margin-bottom: 32px;
}

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-family: 'Inter', sans-serif;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  margin-bottom: 24px;
}
.back-btn:hover {
  background: rgba(255,255,255,0.1);
  color: var(--text-primary);
  border-color: var(--border-glass-hover);
}
.back-arrow { font-size: 16px; }

.subject-header-info {
  display: flex;
  align-items: center;
  gap: 16px;
}

.subject-header-icon {
  width: 56px; height: 56px;
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  font-size: 28px;
}

.subject-header-name {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 28px;
  font-weight: 700;
}

.subject-header-sub {
  font-size: 14px;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* ============================================================
   EXPERIMENT LIST
   ============================================================ */
.exp-list-section { margin-bottom: 40px; }

.exp-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.exp-list-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 20px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-smooth);
}
.exp-list-item:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glass-hover);
  transform: translateX(4px);
  box-shadow: var(--shadow-sm);
}

.exp-item-icon {
  width: 48px; height: 48px;
  border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 22px;
  flex-shrink: 0;
}

.exp-item-info { flex: 1; min-width: 0; }

.exp-item-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.exp-item-desc {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.4;
  display: -webkit-box;
  line-clamp: 2;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.exp-item-arrow {
  font-size: 18px;
  color: var(--text-muted);
  flex-shrink: 0;
  transition: transform var(--transition-fast);
}
.exp-list-item:hover .exp-item-arrow {
  transform: translateX(4px);
}

/* ============================================================
   EXPERIMENT VIEW
   ============================================================ */
.exp-topbar {
  margin-bottom: 24px;
}

.exp-title-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 8px;
}

.exp-subject-badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.exp-subject-badge.badge-physics { background: var(--physics-bg); color: var(--physics-primary); border: 1px solid rgba(59,130,246,0.2); }
.exp-subject-badge.badge-chemistry { background: var(--chemistry-bg); color: var(--chemistry-primary); border: 1px solid rgba(249,115,22,0.2); }
.exp-subject-badge.badge-biology { background: var(--biology-bg); color: var(--biology-primary); border: 1px solid rgba(34,197,94,0.2); }

.exp-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 24px;
  font-weight: 700;
}

.seo-experiment {
  max-width: 1180px;
  margin: 0 auto;
}

.prelab-container {
  max-width: 900px;
  margin: auto;
  margin-bottom: 28px;
}

.prelab-wrapper {
  position: relative;
  border-radius: 18px;
  padding: 1px;
  background: linear-gradient(135deg, rgba(99,102,241,0.45), rgba(139,92,246,0.25), rgba(99,102,241,0.1));
}

.prelab-card {
  background: rgba(10, 12, 28, 0.6);
  backdrop-filter: blur(32px) saturate(1.4);
  -webkit-backdrop-filter: blur(32px) saturate(1.4);
  border-radius: 18px;
  padding: 24px;
  border: 1px solid rgba(255,255,255,0.07);
  box-shadow:
    0 8px 48px rgba(0,0,0,0.6),
    inset 0 1px 0 rgba(255,255,255,0.06);
}

.prelab-panel {
  position: relative;
  padding: 32px;
  overflow: hidden;
}

.prelab-panel::before {
  content: '';
  position: absolute;
  top: -40px;
  right: -40px;
  width: 260px;
  height: 260px;
  background: radial-gradient(circle at center, rgba(99,102,241,0.07), transparent 65%);
  pointer-events: none;
}

.prelab-hero {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  flex-wrap: wrap;
  margin-bottom: 32px;
}

.prelab-meta {
  min-width: 320px;
  flex: 1 1 560px;
}

.prelab-breadcrumb {
  margin: 0 0 14px;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.prelab-breadcrumb a {
  color: var(--physics-primary);
  text-decoration: none;
}

.prelab-title {
  font-size: 20px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
  color: white;
}

.prelab-title::before {
  content: "🧪";
}

.prelab-desc {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.8;
  margin: 18px 0 0;
  max-width: 72ch;
}

.prelab-badge-group {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 24px;
}

.prelab-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 14px;
  border-radius: 999px;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.08);
  color: var(--text-primary);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.prelab-spark {
  min-width: 240px;
  flex: 0 0 260px;
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.07);
  border-radius: 26px;
  padding: 24px;
  display: grid;
  gap: 12px;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
}

.prelab-spark-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--text-secondary);
}

.prelab-spark-value {
  color: var(--text-primary);
  font-size: 1rem;
  line-height: 1.75;
}

.prelab-grid,
.prelab-detail-grid {
  display: grid;
  gap: 18px;
}

.prelab-grid {
  grid-template-columns: repeat(3, minmax(220px, 1fr));
}

.prelab-detail-grid {
  grid-template-columns: 1.2fr 1.5fr;
}

.prelab-card {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--radius-lg);
  padding: 24px;
  min-height: 180px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.prelab-detail-card {
  min-height: auto;
}

.prelab-card-head {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.prelab-card-head span {
  font-size: 1em;
}

.prelab-card p,
.prelab-card ul,
.prelab-card ol {
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.75;
}

.prelab-card ul,
.prelab-card ol {
  padding-left: 20px;
}

.prelab-card li {
  margin-bottom: 10px;
}

.question-block {
  margin-top: 20px;
  padding: 16px;
  border-radius: 12px;
  background: rgba(255,255,255,0.02);
  border: 1px solid rgba(255,255,255,0.04);
}

.question-text {
  font-weight: 500;
  margin-bottom: 10px;
  color: var(--text-primary);
}

.related-experiments h3 {
  margin: 20px 0 10px;
  font-size: 1.2rem;
  color: var(--text-primary);
}

.related-experiments ul {
  list-style: none;
  padding: 0;
}

.related-experiments li {
  margin-bottom: 8px;
}

.related-experiments a {
  color: var(--physics-primary);
  text-decoration: none;
}

.related-experiments a:hover {
  text-decoration: underline;
}

@media (max-width: 960px) {
  .prelab-hero,
  .prelab-grid,
  .prelab-detail-grid {
    grid-template-columns: 1fr;
    flex-direction: column;
  }

  .prelab-hero {
    display: grid;
  }

  .prelab-spark {
    flex: 1 1 auto;
  }
}

@media (max-width: 700px) {
  .prelab-card {
    padding: 20px;
  }

  .prelab-title {
    font-size: 2.4rem;
  }
}

/* ── Lab Record ────────────────────────────────────────────── */
.glass-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  overflow: hidden;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.lab-record { margin-bottom: 20px; }

.lab-record-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  background: none;
  border: none;
  color: var(--text-primary);
  font-family: 'Inter', sans-serif;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--transition-fast);
}
.lab-record-toggle:hover { background: rgba(255,255,255,0.03); }

.toggle-icon {
  font-size: 12px;
  color: var(--text-muted);
  transition: transform var(--transition-fast);
}
.toggle-icon.open { transform: rotate(180deg); }

.lab-record-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
}
.lab-record-body.open {
  max-height: 2000px;
}

.lab-record-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  padding: 0 20px 20px;
}

.lab-record-item {
  padding: 14px 16px;
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
}

.lab-record-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}
.lab-record-label span {
  font-size: 14px;
}
.lab-record-label.lbl-aim { color: var(--physics-primary); }
.lab-record-label.lbl-apparatus { color: var(--chemistry-primary); }
.lab-record-label.lbl-procedure { color: #a855f7; }
.lab-record-label.lbl-precautions { color: #f59e0b; }
.lab-record-label.lbl-conclusion { color: var(--biology-primary); }

.lab-record-text {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.65;
}

.lab-record-list {
  list-style: none;
  padding: 0;
}
.lab-record-list li {
  font-size: 13px;
  color: var(--text-secondary);
  padding: 3px 0 3px 16px;
  position: relative;
  line-height: 1.5;
}
.lab-record-list li::before {
  content: '•';
  position: absolute;
  left: 0;
  color: var(--text-muted);
}

.lab-record-stepper {
  list-style: none;
  padding: 0;
  margin: 0;
}
.step-item {
  display: flex;
  gap: 12px;
  margin-bottom: 10px;
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
}
.step-item:last-child {
  margin-bottom: 0;
}
.step-num {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  background: rgba(255,255,255,0.1);
  border: 1px solid var(--border-glass);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 10px;
  font-weight: 700;
  color: var(--text-primary);
}

/* ── Simulation Area ───────────────────────────────────────── */
.sim-area {
  min-height: 400px;
}

.sim-container {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.sim-canvas-wrap {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  overflow: hidden;
  position: relative;
}

.sim-canvas-wrap canvas {
  display: block;
  width: 100%;
  height: auto;
}

/* Controls Panel */
.sim-controls {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 20px;
}

.sim-controls-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.sim-controls-title .ctrl-icon { font-size: 16px; }

.sim-control-row {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 14px;
}
.sim-control-row:last-child { margin-bottom: 0; }

.sim-control-label {
  font-size: 13px;
  color: var(--text-secondary);
  min-width: 120px;
  font-weight: 500;
}

.sim-control-slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  background: rgba(255,255,255,0.08);
  border-radius: 3px;
  outline: none;
  transition: background var(--transition-fast);
}
.sim-control-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--physics-primary);
  cursor: pointer;
  box-shadow: 0 0 8px rgba(59,130,246,0.4);
  transition: transform var(--transition-fast);
}
.sim-control-slider::-webkit-slider-thumb:hover { transform: scale(1.15); }

.sim-control-slider.slider-chemistry::-webkit-slider-thumb { background: var(--chemistry-primary); box-shadow: 0 0 8px var(--chemistry-glow); }
.sim-control-slider.slider-biology::-webkit-slider-thumb { background: var(--biology-primary); box-shadow: 0 0 8px var(--biology-glow); }

.sim-control-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px;
  color: var(--text-primary);
  min-width: 65px;
  text-align: right;
  font-weight: 500;
}

/* Results Panel */
.sim-results {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 20px;
}

.sim-results-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.sim-result-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
}
.sim-result-row:last-child { margin-bottom: 0; }

.sim-result-label {
  font-size: 13px;
  color: var(--text-secondary);
}

.sim-result-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 15px;
  font-weight: 600;
}

/* ── Unified Button System ────────────────────────────────── */
.sim-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  font-family: 'Inter', sans-serif;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  background: rgba(255,255,255,0.05);
  color: var(--text-primary);
  letter-spacing: 0;
  white-space: nowrap;
}
.sim-btn:hover {
  background: rgba(255,255,255,0.1);
  transform: translateY(-1px);
  border-color: var(--border-glass-hover);
}
.sim-btn:active {
  transform: translateY(0);
}
.sim-btn.btn-primary {
  background: linear-gradient(135deg, #3b82f6, #2563eb);
  border-color: rgba(59, 130, 246, 0.4);
  color: white;
  box-shadow: 0 2px 10px rgba(59, 130, 246, 0.2);
}
.sim-btn.btn-primary:hover {
  background: linear-gradient(135deg, #2563eb, #1d4ed8);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.35);
  transform: translateY(-2px);
}
.sim-btn.btn-secondary {
  background: rgba(255,255,255,0.06);
  border-color: var(--border-glass-hover);
  color: var(--text-primary);
}
.sim-btn.btn-secondary:hover {
  background: rgba(255,255,255,0.12);
}
.sim-btn.btn-ghost {
  background: transparent;
  border-color: transparent;
  color: var(--text-secondary);
}
.sim-btn.btn-ghost:hover {
  background: rgba(255,255,255,0.05);
  color: var(--text-primary);
}

.sim-btn-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

/* Data panel / live data */
.sim-data-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 20px;
}

.sim-data-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 14px;
}

.sim-data-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
}

.sim-data-label {
  font-size: 12px;
  color: var(--text-secondary);
  min-width: 130px;
}

.sim-data-bar-track {
  flex: 1;
  height: 6px;
  background: rgba(255,255,255,0.06);
  border-radius: 3px;
  overflow: hidden;
}
.sim-data-bar-fill {
  height: 100%;
  border-radius: 3px;
  transition: width 0.15s ease;
}

.sim-data-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  color: var(--text-primary);
  min-width: 55px;
  text-align: right;
}

/* ── Notebook ──────────────────────────────────────────────── */
.sim-notebook {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 20px;
}

.sim-notebook-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.sim-notebook-list {
  list-style: none;
  padding: 0;
  max-height: 180px;
  overflow-y: auto;
}

.sim-notebook-list li {
  font-size: 12px;
  color: var(--text-secondary);
  padding: 4px 0;
  padding-left: 14px;
  position: relative;
  line-height: 1.4;
}
.sim-notebook-list li::before {
  content: '•';
  position: absolute;
  left: 0;
  color: var(--text-muted);
}

/* ── Phase Indicator ───────────────────────────────────────── */
.sim-phase-bar {
  display: flex;
  gap: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 14px 16px;
}

.sim-phase-step {
  flex: 1;
  text-align: center;
}

.sim-phase-bar-track {
  height: 4px;
  border-radius: 2px;
  background: rgba(255,255,255,0.08);
  margin-bottom: 6px;
}
.sim-phase-bar-track.done { background: var(--biology-primary); }
.sim-phase-bar-track.active { background: #f59e0b; }

.sim-phase-label {
  font-size: 11px;
  color: var(--text-muted);
}
.sim-phase-label.active { color: var(--text-primary); font-weight: 600; }

/* ============================================================
   RECENT ACTIVITY SECTION
   ============================================================ */
#recent-activity-container {
  margin-bottom: 40px;
}
.recent-activity-card {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 24px 32px;
  background: linear-gradient(135deg, rgba(255,255,255,0.03) 0%, rgba(255,255,255,0) 100%);
  border: 1px solid var(--border-glass);
  box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.3);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}
.recent-activity-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; width: 100%; height: 2px;
  background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.5), transparent);
}
.recent-activity-card:hover {
  border-color: rgba(59, 130, 246, 0.4);
  transform: translateY(-2px);
}
.recent-icon-wrap {
  width: 56px; height: 56px;
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  font-size: 28px;
  flex-shrink: 0;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,0.1);
}
.recent-info {
  flex: 1;
  min-width: 0; /* for truncation if needed */
}
.recent-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
}
.recent-progress-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.recent-progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: var(--text-secondary);
  font-weight: 500;
}
.recent-progress-track {
  width: 100%;
  height: 6px;
  background: rgba(0,0,0,0.4);
  border-radius: 3px;
  box-shadow: inset 0 1px 3px rgba(0,0,0,0.5);
  overflow: hidden;
}
.recent-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #3b82f6, #a855f7);
  border-radius: 3px;
  transition: width 1s cubic-bezier(0.1, 1, 0.2, 1);
  box-shadow: 0 0 10px rgba(168, 85, 247, 0.5);
}
.resume-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  background: var(--physics-primary);
  color: white;
  border: none;
  border-radius: 100px;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.3);
}
.resume-btn:hover {
  background: #2563eb;
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.4);
}
.resume-arrow {
  transition: transform 0.3s ease;
}
.resume-btn:hover .resume-arrow {
  transform: translateX(4px);
}

/* ============================================================
   EXPLORATION SYSTEM
   ============================================================ */
.landing-cta-secondary {
  background: rgba(255,255,255,0.08);
  border: 1px solid var(--border-glass-hover);
  color: var(--text-primary);
  text-decoration: none;
}

.explore-hub-section,
.featured-experiments-section,
.explore-page {
  margin-bottom: 48px;
}

.explore-hub-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.explore-hub-card {
  display: block;
  padding: 22px;
  text-decoration: none;
  color: inherit;
  transition: transform var(--transition-smooth), border-color var(--transition-fast), background var(--transition-fast);
}

.explore-hub-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glass-hover);
  background: var(--bg-card-hover);
}

.explore-hub-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin-bottom: 16px;
  border-radius: 14px;
  background: rgba(255,255,255,0.08);
  font-size: 22px;
}

.explore-hub-card h2,
.explore-exp-card h3 {
  font-family: 'Space Grotesk', sans-serif;
  color: var(--text-primary);
}

.explore-hub-card h2 {
  font-size: 20px;
  margin-bottom: 8px;
}

.explore-hub-card p,
.section-subtitle,
.explore-exp-card p,
.explore-page-hero p {
  color: var(--text-secondary);
}

.section-heading-row {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 20px;
}

.section-link {
  color: var(--physics-primary);
  text-decoration: none;
  font-weight: 700;
}

.explore-exp-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}

.explore-exp-card {
  display: flex;
  min-height: 340px;
  flex-direction: column;
  padding: 0 !important; /* Full-bleed layout to accommodate the top preview banner */
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  color: inherit;
  text-decoration: none;
  overflow: hidden;
  transition: transform var(--transition-smooth), border-color var(--transition-fast), background var(--transition-fast), box-shadow var(--transition-fast);
}

.explore-exp-card:hover {
  transform: translateY(-4px);
  background: var(--bg-card-hover);
}

.explore-exp-card.exp-physics:hover {
  border-color: var(--physics-primary) !important;
  box-shadow: 0 8px 32px var(--physics-glow), 0 0 0 1px var(--physics-bg);
}

.explore-exp-card.exp-chemistry:hover {
  border-color: var(--chemistry-primary) !important;
  box-shadow: 0 8px 32px var(--chemistry-glow), 0 0 0 1px var(--chemistry-bg);
}

.explore-exp-card.exp-biology:hover {
  border-color: var(--biology-primary) !important;
  box-shadow: 0 8px 32px var(--biology-glow), 0 0 0 1px var(--biology-bg);
}

/* ── Card Details Container ── */
.explore-exp-details {
  display: flex;
  flex-direction: column;
  flex: 1;
  padding: 20px;
}

/* ── Card Preview Panel ── */
.explore-exp-preview {
  position: relative;
  width: 100%;
  height: 140px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-glass);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  transition: background var(--transition-fast);
}

.explore-exp-preview-grid {
  position: absolute;
  inset: 0;
  background-image: 
    linear-gradient(rgba(255, 255, 255, 0.01) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.01) 1px, transparent 1px);
  background-size: 20px 20px;
  background-position: center;
  pointer-events: none;
  opacity: 0.5;
}

.exp-svg-preview {
  width: 100%;
  height: 100%;
  max-width: 240px;
  max-height: 120px;
  display: block;
}

/* ── Hover Interaction: Pause/Play SVG Animations ── */
.explore-exp-card .exp-svg-preview * {
  animation-play-state: paused !important;
}

.explore-exp-card:hover .exp-svg-preview * {
  animation-play-state: running !important;
}

/* ── Subject mappings on cards ── */
.explore-exp-card.exp-physics {
  --accent-primary: var(--physics-primary);
  --accent-glow: var(--physics-glow);
  --accent-bg: var(--physics-bg);
}

.explore-exp-card.exp-chemistry {
  --accent-primary: var(--chemistry-primary);
  --accent-glow: var(--chemistry-glow);
  --accent-bg: var(--chemistry-bg);
}

.explore-exp-card.exp-biology {
  --accent-primary: var(--biology-primary);
  --accent-glow: var(--biology-glow);
  --accent-bg: var(--biology-bg);
}

/* ── Status Badges in Topline ── */
.exp-status-group {
  display: flex;
  gap: 6px;
  align-items: center;
  margin-left: auto;
}

.exp-status-pill {
  display: inline-flex;
  align-items: center;
  font-size: 9px;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 100px;
  border: 1px solid rgba(255, 255, 255, 0.04);
  background: rgba(255, 255, 255, 0.02);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.explore-exp-topline,
.explore-exp-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.explore-exp-topline { margin-bottom: 18px; }

.explore-exp-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  font-size: 20px;
}

.explore-exp-card h3 {
  font-size: 20px;
  margin-bottom: 8px;
}

.explore-exp-card p {
  flex: 1;
  font-size: 14px;
  line-height: 1.6;
}

.explore-pill,
.explore-exp-meta span {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  border: 1px solid var(--border-glass);
  background: rgba(255,255,255,0.05);
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 700;
}

.explore-pill { padding: 5px 9px; }
.explore-exp-meta { margin-top: 18px; }
.explore-exp-meta span { padding: 4px 8px; }

.pill-physics { color: #93c5fd; background: var(--physics-bg); }
.pill-chemistry { color: #fdba74; background: var(--chemistry-bg); }
.pill-biology { color: #86efac; background: var(--biology-bg); }

.explore-page {
  padding: 48px 0 70px;
}

.explore-page-hero {
  max-width: 780px;
  margin-bottom: 28px;
}

.explore-page-hero h1 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(38px, 7vw, 68px);
  line-height: 1;
  margin: 12px 0 16px;
}

.filter-panel {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr)) auto;
  gap: 14px;
  align-items: end;
  padding: 18px;
  margin-bottom: 30px;
}

.filter-field label {
  display: block;
  margin-bottom: 7px;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.filter-field select {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,0.06);
  color: var(--text-primary);
  padding: 0 12px;
  font-family: inherit;
  font-weight: 600;
}

.filter-field option { color: #111827; }

.clear-filter-btn {
  min-height: 42px;
  padding: 0 16px;
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,0.06);
  color: var(--text-primary);
  cursor: pointer;
  font-family: inherit;
  font-weight: 800;
}

.clear-filter-btn:hover {
  border-color: var(--border-glass-hover);
  background: rgba(255,255,255,0.1);
}

.filter-empty {
  margin-top: 18px;
  padding: 28px;
  text-align: center;
  color: var(--text-secondary);
}

.related-experiments {
  margin-top: 28px;
}

.related-experiments ul {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 10px;
  list-style: none;
  margin-top: 12px;
}

.related-experiments a {
  display: block;
  padding: 10px 12px;
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  text-decoration: none;
  background: rgba(255,255,255,0.04);
}

.related-experiments a:hover {
  color: var(--text-primary);
  border-color: var(--border-glass-hover);
}


@media (max-width: 640px) {
  .explore-hub-grid,
  .filter-panel { grid-template-columns: 1fr; }
  .section-heading-row { align-items: flex-start; flex-direction: column; }
  .explore-page { padding-top: 28px; }
}

/* ============================================================
   GAMIFICATION & PROFILE
   ============================================================ */
/* Nav Profile Btn */
.nav-profile-btn {
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-glass);
  color: white;
  width: 36px; height: 36px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 16px;
  cursor: pointer;
  transition: all 0.3s ease;
  margin-left: 16px;
}
.nav-profile-btn:hover { background: rgba(59, 130, 246, 0.2); border-color: rgba(59,130,246,0.5); transform: scale(1.05); }

/* Dashboard Rank Card */
.rank-card {
  padding: 24px;
  display: flex; flex-direction: column; gap: 16px;
  position: relative; overflow: hidden;
  transition: all 0.3s ease;
}
.rank-card:hover { transform: translateY(-3px); border-color: rgba(255,255,255,0.15); box-shadow: 0 8px 30px rgba(0,0,0,0.4); }
.rank-card-header { display: flex; align-items: center; gap: 16px; }
.rank-icon-wrap { width: 50px; height: 50px; border-radius: 12px; display: flex; align-items: center; justify-content: center; font-size: 24px; }
.rank-title { font-family: 'Space Grotesk', sans-serif; font-size: 22px; font-weight: 700; }
.rank-progress-labels { display: flex; justify-content: space-between; font-size: 13px; font-weight: 600; margin-bottom: 6px; }
.rank-progress-track { height: 8px; background: rgba(0,0,0,0.3); border-radius: 4px; box-shadow: inset 0 1px 3px rgba(0,0,0,0.5); overflow: hidden; }
.rank-progress-fill { height: 100%; border-radius: 4px; transition: width 1s ease-in-out; }

/* Profile Page */
.profile-glass-header { 
  padding: 40px; display: flex; align-items: center; gap: 30px; margin-bottom: 30px; 
  background: linear-gradient(135deg, rgba(255,255,255,0.05), transparent);
}
.profile-avatar-wrap { width: 100px; height: 100px; border-radius: 20px; display: flex; align-items: center; justify-content: center; font-size: 48px; }
.profile-name { font-family: 'Space Grotesk', sans-serif; font-size: 36px; font-weight: 700; color: white; margin-bottom: 8px; }

.profile-stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px; margin-bottom: 30px; }
.stat-box { padding: 24px; text-align: center; }
.stat-box-title { font-size: 14px; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 1px; font-weight: 600; margin-bottom: 12px; }
.stat-box-val { font-family: 'JetBrains Mono', monospace; font-size: 36px; font-weight: 700; text-shadow: 0 0 15px currentColor; }

.profile-progression { padding: 30px; margin-bottom: 40px; }

/* Badges */
.badges-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 16px; margin-bottom: 40px; }
.profile-badge-card { padding: 20px 10px; background: rgba(255,255,255,0.02); border: 1px solid var(--border-glass); border-radius: 12px; text-align: center; transition: all 0.3s; }
.profile-badge-card.unlocked { background: rgba(255,255,255,0.06); border-color: rgba(255,255,255,0.2); box-shadow: 0 4px 15px rgba(0,0,0,0.2); }
.profile-badge-card.unlocked .badge-icon { animation: floatBadge 4s ease-in-out infinite; filter: none; opacity: 1; }
.profile-badge-card.locked .badge-icon { filter: grayscale(100%) opacity(0.3); }
.badge-icon { font-size: 40px; margin-bottom: 12px; }
.badge-name { font-size: 13px; font-weight: 600; margin-bottom: 4px; color: var(--text-primary); }
.profile-badge-card.locked .badge-name { color: var(--text-muted); }
.badge-desc { font-size: 11px; color: var(--text-secondary); }

@keyframes floatBadge { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-5px); } }

/* Leaderboard */
.leaderboard-card { padding: 20px; }
.leaderboard-table { width: 100%; border-collapse: collapse; text-align: left; }
.leaderboard-table th { padding: 12px 16px; font-size: 12px; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; border-bottom: 1px solid var(--border-glass); }
.leaderboard-table td { padding: 16px; border-bottom: 1px solid rgba(255,255,255,0.02); }
.leaderboard-table tr:last-child td { border-bottom: none; }
.leaderboard-table tr.lb-me { background: rgba(59, 130, 246, 0.1); }
.leaderboard-table tr:hover { background: rgba(255,255,255,0.03); }

/* Toasts & Modals */
.xp-toast { position: fixed; bottom: 30px; right: 30px; background: rgba(16, 185, 129, 0.2); border: 1px solid #10b981; color: #10b981; padding: 12px 24px; border-radius: 100px; font-weight: 700; font-family: 'JetBrains Mono', monospace; z-index: 1000; animation: slideUp 0.3s ease-out, fadeOut 0.5s ease-in 2s forwards; backdrop-filter: blur(10px); }
.badge-toast { position: fixed; top: 100px; right: 20px; display: flex; align-items: center; gap: 16px; padding: 16px 20px; z-index: 1000; animation: slideInRight 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275), fadeOut 0.5s ease-in 3.5s forwards; }
.rankup-modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.8); backdrop-filter: blur(8px); z-index: 2000; display: flex; align-items: center; justify-content: center; animation: fadeIn 0.3s ease; }
.rankup-modal-content { padding: 50px; min-width: 400px; animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275); }

@keyframes slideUp { from { transform: translateY(20px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }
@keyframes slideInRight { from { transform: translateX(50px); opacity: 0; } to { transform: translateX(0); opacity: 1; } }
@keyframes fadeOut { to { opacity: 0; visibility: hidden; } }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes popIn { from { transform: scale(0.8); opacity: 0; } to { transform: scale(1); opacity: 1; } }
@keyframes pop { 0% { transform: scale(1); } 50% { transform: scale(1.3); } 100% { transform: scale(1); } }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 768px) {
  :root {
    --section-gap: 40px;
  }
  .navbar-inner { padding: 0 16px; }
  .main-container { padding: 80px 16px 40px; }
  .subject-grid { grid-template-columns: 1fr; }
  .hero-title { font-size: 28px; }
  .hero-section { padding: 32px 0 var(--section-gap); }
  .stats-bar { gap: 16px; padding: 20px; flex-wrap: wrap; }
  .stat-divider { display: none; }
  .sim-control-row { flex-wrap: wrap; }
  .sim-control-label { min-width: 100%; }
  .exp-topbar { margin-bottom: 16px; }
  .subject-header { margin-bottom: 24px; }
  .landing-hero { min-height: 100svh; padding: 80px 20px 60px; }
  .landing-title { font-size: 36px; }
  .landing-desc { font-size: 15px; }
  .landing-pills { gap: 8px; }
  .landing-pill { font-size: 11px; padding: 5px 10px; }
  .landing-cta-btn { padding: 16px 36px; font-size: 15px; }
}

@media (max-width: 480px) {
  .subject-card { padding: 20px; }
  .exp-list-item { padding: 16px; }
  .landing-title { font-size: 30px; }
  .landing-badge { font-size: 11px; padding: 5px 12px; }
}

/* ============================================================
   PHOTOSYNTHESIS STARCH TEST — Experiment Styles
   ============================================================ */
.ps-root { display: flex; flex-direction: column; gap: 14px; padding: 4px 0; }

.ps-topbar {
  display: flex; align-items: center; gap: 16px;
  padding: 12px 16px;
  background: rgba(15,20,30,0.6);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  flex-wrap: wrap;
}
.ps-progress-wrap { flex: 1; display: flex; align-items: center; gap: 12px; min-width: 180px; }
.ps-progress-label { font-size: 12px; font-weight: 600; color: var(--biology-primary); font-family: 'JetBrains Mono', monospace; white-space: nowrap; }
.ps-progress-track { flex: 1; height: 6px; background: rgba(255,255,255,0.08); border-radius: 100px; overflow: hidden; }
.ps-progress-fill { height: 100%; background: linear-gradient(90deg, var(--biology-primary), #84cc16); border-radius: 100px; transition: width 0.5s cubic-bezier(0.4,0,0.2,1); box-shadow: 0 0 8px rgba(34,197,94,0.4); }
.ps-top-btns { display: flex; gap: 8px; flex-wrap: wrap; }
.ps-ctrl-btn { display: inline-flex; align-items: center; gap: 6px; padding: 7px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border-glass); background: rgba(255,255,255,0.05); color: var(--text-secondary); font-family: 'Inter', sans-serif; font-size: 12px; font-weight: 500; cursor: pointer; transition: all var(--transition-fast); }
.ps-ctrl-btn:hover { background: rgba(255,255,255,0.1); color: var(--text-primary); border-color: var(--border-glass-hover); }
.ps-ctrl-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.ps-demo-btn { background: rgba(34,197,94,0.1); border-color: rgba(34,197,94,0.25); color: var(--biology-primary); }
.ps-demo-btn:hover { background: rgba(34,197,94,0.2); border-color: rgba(34,197,94,0.5); color: #4ade80; }
.ps-reset-btn { background: rgba(239,68,68,0.08); border-color: rgba(239,68,68,0.2); color: #f87171; }
.ps-reset-btn:hover { background: rgba(239,68,68,0.15); border-color: rgba(239,68,68,0.4); }
.ps-hint-btn.ps-hint-active { background: rgba(245,158,11,0.15); border-color: rgba(245,158,11,0.35); color: #fbbf24; }

.ps-main-grid { display: grid; grid-template-columns: 220px 1fr 240px; gap: 14px; min-height: 480px; }

.ps-sidebar { background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); padding: 14px 10px; display: flex; flex-direction: column; gap: 4px; overflow-y: auto; }
.ps-sidebar-title { font-size: 11px; font-weight: 600; text-transform: uppercase; letter-spacing: 1px; color: var(--text-muted); padding: 0 6px; margin-bottom: 8px; }
.ps-step-item { display: flex; align-items: flex-start; gap: 8px; padding: 9px 8px; border-radius: 8px; cursor: pointer; border: 1px solid transparent; transition: all var(--transition-fast); }
.ps-step-item:hover { background: rgba(255,255,255,0.04); border-color: var(--border-glass); }
.ps-step-item.ps-step-active { background: rgba(34,197,94,0.1); border-color: rgba(34,197,94,0.3); box-shadow: 0 0 12px rgba(34,197,94,0.12); }
.ps-step-item.ps-step-done { background: rgba(34,197,94,0.06); border-color: rgba(34,197,94,0.15); }
.ps-step-item.ps-step-locked { opacity: 0.45; cursor: not-allowed; }
.ps-step-num {
  font-size: 10px;
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-muted);
  min-width: 14px;
  padding-top: 1px;
}

/* ============================================================
   REUSABLE UI DESIGN SYSTEM
   ============================================================ */

/* 1. Glass Card - Standardized for lab sections */
.glass-card {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-md);
  transition: all var(--transition-smooth);
}

/* 2. Glow Border - RGB Neon effect */
.glow-border {
  position: relative;
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  background: linear-gradient(var(--bg-card), var(--bg-card)) padding-box,
              linear-gradient(135deg, #00f2ff, #7000ff, #00f2ff) border-box;
  transition: all var(--transition-smooth);
}
.glow-border:hover {
  box-shadow: 0 0 20px rgba(112, 0, 255, 0.3), 0 0 10px rgba(0, 242, 255, 0.2);
  transform: translateY(-2px);
}

/* 3. Section Title - Glowing & Bold */
.section-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  display: block;
  text-shadow: 0 0 10px rgba(59, 130, 246, 0.5);
  letter-spacing: -0.02em;
}

/* 4. Interactive Block - Slightly brighter glass */
.interactive-block {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--border-glass-hover);
  border-radius: var(--radius-sm);
  padding: 16px;
  transition: all var(--transition-fast);
  cursor: pointer;
}
.interactive-block:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: var(--physics-primary);
  transform: scale(1.01);
}

/* 5. Primary Button - Glowing & Rounded */
.primary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  border: 2px solid #00f2ff;
  border-radius: 100px;
  background: transparent;
  color: var(--text-primary);
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-smooth);
  text-decoration: none;
  box-shadow: 0 0 10px rgba(0, 242, 255, 0.2);
}
.primary-button:hover {
  background: #00f2ff;
  color: var(--bg-primary);
  box-shadow: 0 0 20px rgba(0, 242, 255, 0.6);
  transform: scale(1.05);
}

.ps-step-active .ps-step-num { color: var(--biology-primary); }
.ps-step-done .ps-step-num { color: #4ade80; }
.ps-step-icon { font-size: 16px; flex-shrink: 0; }
.ps-step-info { flex: 1; min-width: 0; }
.ps-step-name { font-size: 12px; font-weight: 500; color: var(--text-secondary); line-height: 1.3; }
.ps-step-active .ps-step-name { color: var(--text-primary); }
.ps-step-done .ps-step-name { color: #86efac; }
.ps-step-hint { font-size: 11px; color: var(--text-muted); margin-top: 4px; line-height: 1.4; }
.ps-step-hint.hidden { display: none; }
.ps-step-check { font-size: 13px; color: var(--text-muted); min-width: 16px; text-align: right; }
.ps-step-done .ps-step-check { color: #4ade80; }
.ps-step-active .ps-step-check { color: var(--biology-primary); }
.ps-sidebar-note { font-size: 11px; color: var(--text-muted); text-align: center; padding: 8px 6px 0; border-top: 1px solid var(--border-glass); margin-top: 8px; line-height: 1.4; }

.ps-sim-center { display: flex; flex-direction: column; gap: 10px; }
.ps-canvas-wrap { position: relative; border-radius: var(--radius-md); overflow: hidden; border: 1px solid var(--border-glass); background: #060810; width: 100%; aspect-ratio: 520 / 380; }
.ps-canvas-wrap canvas { width: 100%; height: 100%; display: block; }
.ps-canvas-overlay { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; background: rgba(6,8,16,0.82); backdrop-filter: blur(4px); z-index: 10; }
.ps-start-card { text-align: center; padding: 32px 28px; max-width: 340px; }
.ps-start-icon { font-size: 52px; margin-bottom: 12px; animation: psLeafPulse 2.5s ease-in-out infinite; }
@keyframes psLeafPulse { 0%,100% { transform: scale(1) rotate(-3deg); } 50% { transform: scale(1.1) rotate(3deg); } }
.ps-start-card h3 { font-family: 'Space Grotesk', sans-serif; font-size: 18px; font-weight: 700; color: var(--text-primary); margin-bottom: 8px; }
.ps-start-card p { font-size: 13px; color: var(--text-secondary); line-height: 1.6; margin-bottom: 20px; }
.ps-big-btn { display: inline-block; padding: 10px 24px; background: linear-gradient(135deg, var(--biology-primary), #84cc16); color: #fff; font-family: 'Inter', sans-serif; font-size: 14px; font-weight: 600; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: all var(--transition-fast); box-shadow: 0 4px 16px rgba(34,197,94,0.3); }
.ps-big-btn:hover { transform: translateY(-2px); box-shadow: 0 6px 24px rgba(34,197,94,0.45); }
.ps-feedback-banner { padding: 10px 16px; border-radius: var(--radius-sm); font-size: 13px; font-weight: 500; animation: psFadeSlide 0.3s ease; }
@keyframes psFadeSlide { from { opacity:0; transform:translateY(-6px); } to { opacity:1; transform:translateY(0); } }
.ps-feedback-banner.hidden { display: none; }
.ps-fb-success { background: rgba(34,197,94,0.15); border: 1px solid rgba(34,197,94,0.3); color: #4ade80; }
.ps-fb-error   { background: rgba(239,68,68,0.15);  border: 1px solid rgba(239,68,68,0.3);  color: #f87171; }
.ps-fb-warn    { background: rgba(245,158,11,0.15); border: 1px solid rgba(245,158,11,0.3); color: #fbbf24; }
.ps-step-desc-box { display: flex; align-items: flex-start; gap: 8px; padding: 10px 14px; background: rgba(15,20,30,0.5); border: 1px solid var(--border-glass); border-radius: var(--radius-sm); font-size: 13px; color: var(--text-secondary); line-height: 1.5; }
.ps-step-desc-icon { flex-shrink: 0; }

.ps-info-panel { display: flex; flex-direction: column; gap: 10px; overflow-y: auto; }
.ps-panel-section { background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); padding: 14px; }
.ps-panel-title { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: var(--biology-primary); margin-bottom: 10px; }
.ps-obs-items { display: flex; flex-direction: column; gap: 8px; }
.ps-obs-row { display: flex; justify-content: space-between; align-items: center; font-size: 12px; gap: 8px; }
.ps-obs-label { color: var(--text-muted); flex-shrink: 0; }
.ps-obs-value { font-weight: 600; color: var(--text-secondary); text-align: right; font-size: 12px; transition: color 0.5s ease; }
.ps-obs-form { display: flex; flex-direction: column; gap: 8px; }
.ps-obs-form-label { font-size: 11px; color: var(--text-muted); }
.ps-obs-select { width: 100%; padding: 7px 10px; background: rgba(255,255,255,0.05); border: 1px solid var(--border-glass); border-radius: 6px; color: var(--text-primary); font-family: 'Inter', sans-serif; font-size: 12px; cursor: pointer; }
.ps-obs-select option { background: #0f172a; }
.ps-obs-submit-btn { padding: 8px 12px; background: rgba(34,197,94,0.15); border: 1px solid rgba(34,197,94,0.3); border-radius: 6px; color: var(--biology-primary); font-family: 'Inter', sans-serif; font-size: 12px; font-weight: 600; cursor: pointer; transition: all var(--transition-fast); margin-top: 4px; }
.ps-obs-submit-btn:hover { background: rgba(34,197,94,0.25); }
.ps-obs-submit-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.ps-obs-result { font-size: 12px; padding: 8px 10px; border-radius: 6px; line-height: 1.5; }
.ps-obs-result.hidden { display: none; }
.ps-obs-correct { background: rgba(34,197,94,0.12); color: #4ade80; border: 1px solid rgba(34,197,94,0.25); }
.ps-obs-wrong   { background: rgba(239,68,68,0.10); color: #f87171; border: 1px solid rgba(239,68,68,0.25); }
.ps-result-box { font-size: 13px; color: var(--text-secondary); line-height: 1.65; }
.ps-viva-open-btn { width: 100%; padding: 12px; background: linear-gradient(135deg, rgba(99,102,241,0.2), rgba(139,92,246,0.2)); border: 1px solid rgba(99,102,241,0.35); border-radius: var(--radius-sm); color: #a5b4fc; font-family: 'Inter', sans-serif; font-size: 13px; font-weight: 600; cursor: pointer; transition: all var(--transition-fast); }
.ps-viva-open-btn:hover { background: linear-gradient(135deg, rgba(99,102,241,0.3), rgba(139,92,246,0.3)); border-color: rgba(99,102,241,0.5); transform: translateY(-1px); }

.ps-viva-overlay { position: fixed; inset: 0; z-index: 9999; display: flex; align-items: center; justify-content: center; background: rgba(0,0,0,0.75); backdrop-filter: blur(8px); padding: 20px; animation: psFadeSlide 0.25s ease; }
.ps-viva-overlay.hidden { display: none; }
.ps-viva-modal { background: rgba(10,14,26,0.98); border: 1px solid var(--border-glass-hover); border-radius: var(--radius-lg); width: 100%; max-width: 560px; max-height: 88vh; overflow-y: auto; box-shadow: 0 24px 80px rgba(0,0,0,0.7); }
.ps-viva-header { display: flex; align-items: center; gap: 12px; padding: 18px 20px 14px; border-bottom: 1px solid var(--border-glass); }
.ps-viva-title { font-family: 'Space Grotesk', sans-serif; font-size: 17px; font-weight: 700; color: var(--text-primary); flex: 1; }
.ps-viva-score-label { font-size: 13px; color: var(--text-secondary); }
.ps-viva-close { width: 28px; height: 28px; border-radius: 50%; border: 1px solid var(--border-glass); background: transparent; color: var(--text-muted); cursor: pointer; font-size: 13px; transition: all var(--transition-fast); display: flex; align-items: center; justify-content: center; }
.ps-viva-close:hover { background: rgba(239,68,68,0.15); color: #f87171; border-color: rgba(239,68,68,0.3); }
.ps-viva-progress-bar { height: 3px; background: rgba(255,255,255,0.06); }
.ps-viva-progress-fill { height: 100%; background: linear-gradient(90deg, #6366f1, #a855f7); transition: width 0.4s ease; }
.ps-viva-q { padding: 24px 20px; display: flex; flex-direction: column; gap: 14px; }
.ps-viva-qnum { font-size: 11px; font-weight: 600; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; }
.ps-viva-qtext { font-family: 'Space Grotesk', sans-serif; font-size: 16px; font-weight: 600; color: var(--text-primary); line-height: 1.5; }
.ps-viva-options { display: flex; flex-direction: column; gap: 8px; }
.ps-viva-opt { padding: 12px 16px; background: rgba(255,255,255,0.04); border: 1px solid var(--border-glass); border-radius: 8px; color: var(--text-secondary); font-family: 'Inter', sans-serif; font-size: 13px; font-weight: 500; text-align: left; cursor: pointer; transition: all var(--transition-fast); }
.ps-viva-opt:hover:not(:disabled) { background: rgba(99,102,241,0.12); border-color: rgba(99,102,241,0.3); color: var(--text-primary); }
.ps-viva-opt:disabled { cursor: not-allowed; }
.ps-viva-opt.ps-vopt-correct { background: rgba(34,197,94,0.15); border-color: rgba(34,197,94,0.45); color: #4ade80; }
.ps-viva-opt.ps-vopt-wrong { background: rgba(239,68,68,0.12); border-color: rgba(239,68,68,0.4); color: #f87171; }
.ps-viva-exp { font-size: 13px; padding: 10px 14px; border-radius: 8px; line-height: 1.6; }
.ps-viva-exp.hidden { display: none; }
.ps-exp-correct { background: rgba(34,197,94,0.1); color: #86efac; border: 1px solid rgba(34,197,94,0.2); }
.ps-exp-wrong   { background: rgba(239,68,68,0.10); color: #fca5a5; border: 1px solid rgba(239,68,68,0.2); }
.ps-viva-summary { text-align: center; padding: 32px 24px; display: flex; flex-direction: column; align-items: center; gap: 8px; }
.ps-viva-grade { font-size: 32px; margin-bottom: 4px; }
.ps-viva-final-score { font-family: 'Space Grotesk', sans-serif; font-size: 48px; font-weight: 700; color: var(--text-primary); }
.ps-viva-final-pct { font-size: 16px; color: var(--biology-primary); font-weight: 600; }

@media (max-width: 900px) {
  .ps-main-grid { grid-template-columns: 1fr; }
  .ps-sidebar { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; }
  .ps-sidebar-title, .ps-sidebar-note { grid-column: 1 / -1; }
  .ps-info-panel { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
}
@media (max-width: 600px) {
  .ps-sidebar { grid-template-columns: 1fr 1fr; }
  .ps-info-panel { display: grid; grid-template-columns: 1fr; }
  .ps-top-btns { width: 100%; }
}

/* =======================
   PRE-LAB SECTION (STRICT)
   ======================= */
.prelab-container {
  max-width: 900px;
  margin: auto;
}

.prelab-wrapper {
  position: relative;
  border-radius: 18px;
  padding: 1px;
  background: linear-gradient(120deg, #00f0ff, #7a5cff, #ff2fd1);
}

.prelab-card {
  background: rgba(10, 15, 30, 0.75);
  backdrop-filter: blur(18px);
  border-radius: 18px;
  padding: 24px;
  border: 1px solid rgba(255,255,255,0.05);
  box-shadow:
    0 0 40px rgba(0,0,0,0.8),
    inset 0 0 20px rgba(0,255,255,0.03);
}

.prelab-title {
  font-size: 20px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
  color: white;
}

.prelab-title::before {
  content: "🧪";
}

.question-block {
  margin-top: 20px;
  padding: 16px;
  border-radius: 12px;
  background: rgba(255,255,255,0.02);
  border: 1px solid rgba(255,255,255,0.04);
}

.question-text {
  font-weight: 500;
  margin-bottom: 10px;
  color: white;
}

.prelab-option {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px;
  border-radius: 10px;
  margin: 6px 0;
  background: rgba(255,255,255,0.01);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s ease;
  color: rgba(255,255,255,0.8);
}

.prelab-option:hover {
  border-color: rgba(0,255,255,0.4);
  background: rgba(0,255,255,0.05);
  color: white;
}

.prelab-option.selected {
  border-color: #00f0ff;
  background: rgba(0,240,255,0.12);
  box-shadow: 0 0 10px rgba(0,240,255,0.4);
  color: white;
}

.prelab-submit {
  margin-top: 20px;
  padding: 12px 20px;
  border-radius: 10px;
  border: none;
  background: linear-gradient(120deg, #00f0ff, #7a5cff);
  color: white;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 0 15px rgba(0,240,255,0.4);
  transition: all 0.2s ease;
}

.prelab-submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 25px rgba(0,240,255,0.7);
}

/* Feedback for options when answer is revealed */
.prelab-option.correct {
  border-color: #00ff88 !important;
  background: rgba(0,255,136,0.1) !important;
}
.prelab-option.wrong {
  border-color: #ff4d4d !important;
  background: rgba(255,77,77,0.1) !important;
}
.prelab-exp {
  margin-top: 12px;
  padding: 12px;
  border-radius: 8px;
  font-size: 14px;
  background: rgba(255,255,255,0.05);
  border-left: 3px solid #00f0ff;
  color: rgba(255,255,255,0.9);
}

.prelab-container {
  max-width: 900px;
  margin: 40px auto;
}
.prelab-wrapper {
  border-radius: 22px;
  padding: 2px;
  background: linear-gradient(115deg, #00f0ff, #7a5cff, #ff2fd1);
  box-shadow: 0 0 42px 0 #00f0ff52;
}

.prelab-card.prelab-glass {
  background: rgba(10, 15, 30, 0.72);
  border-radius: 20px;
  padding: 32px 28px;
  border: 2.2px solid transparent;
  box-shadow:
    0 0 38px #00f0ff33,
    inset 0 0 22px #7a5cff11;
  backdrop-filter: blur(18px) saturate(1.5);
  position: relative;
  z-index: 1;
}
.prelab-card {
  color: #f7fbfc;
  text-shadow: 0 1px 3px #09101b96;
}

.prelab-title {
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 800;
  font-size: 23px;
  letter-spacing: 0.04em;
  color: #fff;
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}
.prelab-title-icon {
  font-size: 1.2em;
  filter: drop-shadow(0 0 2px #00f0ff) drop-shadow(0 0 6px #7a5cff77);
}
.prelab-progress-bar {
  background: rgba(255,255,255,0.07);
  border-radius: 4px;
  height: 6px;
  overflow: hidden;
  margin-bottom: 20px;
}
.prelab-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--prelab-glow-1), var(--prelab-glow-3));
  border-radius: 4px;
  transition: width 0.45s cubic-bezier(.65,.05,.36,1);
  box-shadow: 0 0 16px #00f0ff99;
}
.prelab-question-block {
  background: rgba(20,24,40, 0.90);
  border: 1.5px solid rgba(255,255,255,0.06);
  border-radius: 12px;
  margin: 18px 0;
  color: #f6fbff;
  font-family: 'Inter', 'Space Grotesk', sans-serif;
  font-weight: 500;
  box-shadow: 0 0 6px #00f0ff22 inset;
  padding: 20px 0 16px 0;
}
.prelab-q-number {
  font-size: 13px;
  color: #7a5cffcc;
  font-weight: bold;
  margin-bottom: 7px;
  letter-spacing: 1px;
}
.prelab-q-text {
  font-weight: 600;
  color: #fff;
  font-size: 18px;
  margin-bottom: 14px;
}
.prelab-options {
  display: flex;
  flex-direction: column;
  gap: 11px;
}
.prelab-option {
  background: rgba(30,35,50,0.90);
  color: #dde8fd !important;
  border: 1.5px solid rgba(255,255,255,0.10);
  border-radius: 10px;
  margin: 9px 0;
  padding: 15px 18px;
  font-size: 16px;
  font-weight: 600;
  transition: border-color 0.22s, box-shadow 0.2s, background 0.22s;
  cursor: pointer;
  box-shadow: 0 0 0 1.5px #00f0ff80;
}
.prelab-option.selected,
.prelab-option:hover {
  border: 1.5px solid #00f0ff;
  background: rgba(0,240,255, 0.10);
  color: #fff !important;
  box-shadow: 0 0 10px 1px #7a5cff70, 0 0 2px 0.5px #ff2fd170;
}

.prelab-exp {
  margin-top: 18px;
  padding: 12px 16px;
  border-radius: 9px;
  font-size: 14px;
  color: #b9faff;
  border: 1.5px solid #00f0ff44;
  background: rgba(0,240,255,0.08);
  box-shadow: 0 0 14px #7a5cff44 inset;
}
.prelab-correct { border-color: #00ff70dd; color: #c6ffec; }
.prelab-wrong { border-color: #ff2fd1cc; color: #ffd6f7; }
.prelab-submit {
  margin-top: 22px;
  padding: 14px 30px;
  border-radius: 10px;
  border: none;
  background: linear-gradient(120deg, var(--prelab-glow-1), var(--prelab-glow-2));
  color: white;
  font-weight: 700;
  font-size: 16px;
  cursor: pointer;
  box-shadow: 0 0 16px #00f0ff77, 0 0 28px #7a5cff66;
  transition: all 0.2s cubic-bezier(.65,.05,.36,1);
}
.prelab-submit:hover {
  transform: translateY(-2px) scale(1.05);
  box-shadow: 0 0 32px #00f0ffbb, 0 0 48px #7a5cff99;
}

/* ============================================================
   WATER TRANSPORT STARCH TEST — Experiment Styles
   ============================================================ */
.wt-root { display: flex; flex-direction: column; gap: 14px; padding: 4px 0; }
.wt-topbar { display: flex; align-items: center; gap: 16px; padding: 12px 16px; background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); flex-wrap: wrap; }
.wt-prog-wrap { flex: 1; display: flex; align-items: center; gap: 12px; min-width: 180px; }
.wt-prog-label { font-size: 12px; font-weight: 600; color: var(--biology-primary); font-family: 'JetBrains Mono', monospace; white-space: nowrap; }
.wt-prog-track { flex: 1; height: 6px; background: rgba(255,255,255,0.08); border-radius: 100px; overflow: hidden; }
.wt-prog-fill { height: 100%; background: linear-gradient(90deg, var(--biology-primary), #06b6d4); border-radius: 100px; transition: width 0.5s cubic-bezier(0.4,0,0.2,1); box-shadow: 0 0 8px rgba(6,182,212,0.4); }
.wt-top-btns { display: flex; gap: 8px; flex-wrap: wrap; }
.wt-btn { display: inline-flex; align-items: center; gap: 6px; padding: 7px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border-glass); background: rgba(255,255,255,0.05); color: var(--text-secondary); font-family: 'Inter', sans-serif; font-size: 12px; font-weight: 500; cursor: pointer; transition: all var(--transition-fast); }
.wt-btn:hover { background: rgba(255,255,255,0.1); color: var(--text-primary); border-color: var(--border-glass-hover); }
.wt-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.wt-btn-toggle.wt-btn-on { background: rgba(6,182,212,0.15); border-color: rgba(6,182,212,0.4); color: #22d3ee; }
.wt-btn-demo { background: rgba(34,197,94,0.1); border-color: rgba(34,197,94,0.25); color: var(--biology-primary); }
.wt-btn-demo:hover { background: rgba(34,197,94,0.2); border-color: rgba(34,197,94,0.5); color: #4ade80; }
.wt-btn-reset { background: rgba(239,68,68,0.08); border-color: rgba(239,68,68,0.2); color: #f87171; }
.wt-btn-reset:hover { background: rgba(239,68,68,0.15); border-color: rgba(239,68,68,0.4); }

.wt-grid { display: grid; grid-template-columns: 220px 1fr 240px; gap: 14px; min-height: 480px; }
.wt-sidebar { background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); padding: 14px 10px; display: flex; flex-direction: column; gap: 4px; overflow-y: auto; }
.wt-sidebar-hd { font-size: 11px; font-weight: 600; text-transform: uppercase; letter-spacing: 1px; color: var(--text-muted); padding: 0 6px; margin-bottom: 8px; }
.wt-step { display: flex; align-items: flex-start; gap: 8px; padding: 9px 8px; border-radius: 8px; cursor: pointer; border: 1px solid transparent; transition: all var(--transition-fast); }
.wt-step:hover { background: rgba(255,255,255,0.04); border-color: var(--border-glass); }
.wt-s-active { background: rgba(6,182,212,0.1); border-color: rgba(6,182,212,0.3); box-shadow: 0 0 12px rgba(6,182,212,0.12); }
.wt-s-done { background: rgba(6,182,212,0.06); border-color: rgba(6,182,212,0.15); }
.wt-s-lock { opacity: 0.45; cursor: not-allowed; }
.wt-s-num { font-size: 10px; font-weight: 700; font-family: 'JetBrains Mono', monospace; color: var(--text-muted); min-width: 14px; padding-top: 1px; }
.wt-s-active .wt-s-num { color: #06b6d4; }
.wt-s-done .wt-s-num { color: #22d3ee; }
.wt-s-ico { font-size: 16px; flex-shrink: 0; }
.wt-s-name { flex: 1; font-size: 12px; font-weight: 500; color: var(--text-secondary); line-height: 1.3; }
.wt-s-active .wt-s-name { color: var(--text-primary); }
.wt-s-done .wt-s-name { color: #67e8f9; }
.wt-s-chk { font-size: 13px; color: var(--text-muted); min-width: 16px; text-align: right; }
.wt-s-done .wt-s-chk { color: #22d3ee; }
.wt-s-active .wt-s-chk { color: #06b6d4; }
.wt-sidebar-note { font-size: 11px; color: var(--text-muted); text-align: center; padding: 8px 6px 0; border-top: 1px solid var(--border-glass); margin-top: 8px; line-height: 1.4; }

.wt-sim-col { display: flex; flex-direction: column; gap: 10px; }
.wt-picker-row { display: flex; gap: 12px; flex-wrap: wrap; background: rgba(15,20,30,0.5); padding: 10px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border-glass); }
.wt-picker-section { display: flex; flex-direction: column; gap: 6px; border-right: 1px solid rgba(255,255,255,0.05); padding-right: 12px; }
.wt-picker-section:last-child { border-right: none; padding-right: 0; }
.wt-picker-lbl { font-size: 10px; font-weight: 600; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.5px; }
.wt-plant-row { display: flex; gap: 6px; }
.wt-plant-chip { padding: 4px 8px; font-size: 11px; background: rgba(255,255,255,0.05); border: 1px solid var(--border-glass); border-radius: 4px; cursor: pointer; transition: all 0.2s; color: var(--text-secondary); white-space: nowrap; }
.wt-plant-chip:hover { background: rgba(255,255,255,0.1); color: var(--text-primary); }
.wt-plant-chip.wt-chip-active { background: rgba(6,182,212,0.15); border-color: rgba(6,182,212,0.4); color: #22d3ee; }
.wt-dye-row { display: flex; gap: 6px; }
.wt-dye-dot { width: 22px; height: 22px; border-radius: 50%; cursor: pointer; border: 2px solid transparent; transition: transform 0.2s, border-color 0.2s; }
.wt-dye-dot:hover { transform: scale(1.1); }
.wt-dye-dot.wt-dye-active { border-color: white; transform: scale(1.15); box-shadow: 0 0 10px currentColor; }
.wt-slider { -webkit-appearance: none; appearance: none; width: 80px; height: 4px; background: rgba(255,255,255,0.1); border-radius: 2px; }
.wt-slider::-webkit-slider-thumb { -webkit-appearance: none; appearance: none; width: 14px; height: 14px; background: #06b6d4; border-radius: 50%; cursor: pointer; }
.wt-spd-val { font-size: 11px; color: var(--text-secondary); font-variant-numeric: tabular-nums; min-width: 20px; }

.wt-canvas-wrap { position: relative; border-radius: var(--radius-md); overflow: hidden; border: 1px solid var(--border-glass); background: #060810; width: 100%; aspect-ratio: 560 / 400; }
.wt-canvas-wrap canvas { width: 100%; height: 100%; display: block; }
.wt-overlay { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; background: rgba(6,8,16,0.82); backdrop-filter: blur(4px); z-index: 10; }
.wt-start-card { text-align: center; padding: 32px 28px; max-width: 340px; }
.wt-start-ico { font-size: 52px; margin-bottom: 12px; animation: wtFloat 3s ease-in-out infinite; }
@keyframes wtFloat { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }
.wt-start-card h3 { font-family: 'Space Grotesk', sans-serif; font-size: 18px; font-weight: 700; color: var(--text-primary); margin-bottom: 8px; }
.wt-start-card p { font-size: 13px; color: var(--text-secondary); line-height: 1.6; margin-bottom: 20px; }
.wt-big-btn { display: inline-block; padding: 10px 24px; background: linear-gradient(135deg, #0284c7, #06b6d4); color: #fff; font-family: 'Inter', sans-serif; font-size: 14px; font-weight: 600; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: all var(--transition-fast); box-shadow: 0 4px 16px rgba(6,182,212,0.3); }
.wt-big-btn:hover { transform: translateY(-2px); box-shadow: 0 6px 24px rgba(6,182,212,0.45); }

.wt-fb { padding: 8px 12px; border-radius: var(--radius-sm); font-size: 12px; font-weight: 500; animation: psFadeSlide 0.3s ease; }
.wt-fb.hidden { display: none; }
.wt-fb-success { background: rgba(34,197,94,0.15); border: 1px solid rgba(34,197,94,0.3); color: #4ade80; }
.wt-fb-error   { background: rgba(239,68,68,0.15);  border: 1px solid rgba(239,68,68,0.3);  color: #f87171; }
.wt-fb-warn    { background: rgba(245,158,11,0.15); border: 1px solid rgba(245,158,11,0.3); color: #fbbf24; }
.wt-desc-box { display: flex; align-items: flex-start; gap: 8px; padding: 10px 14px; background: rgba(15,20,30,0.5); border: 1px solid var(--border-glass); border-radius: var(--radius-sm); font-size: 13px; color: var(--text-secondary); line-height: 1.5; }

.wt-panel { display: flex; flex-direction: column; gap: 10px; overflow-y: auto; }
.wt-panel-sec { background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); padding: 14px; }
.wt-panel-hd { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: #06b6d4; margin-bottom: 10px; }
.wt-obs-list { display: flex; flex-direction: column; gap: 8px; }
.wt-obs-row { display: flex; justify-content: space-between; align-items: center; font-size: 12px; gap: 8px; }
.wt-obs-k { color: var(--text-muted); flex-shrink: 0; }
.wt-obs-v { font-weight: 600; color: var(--text-secondary); text-align: right; font-size: 12px; }
.wt-form-lbl { font-size: 11px; color: var(--text-muted); display: block; margin-bottom: 4px; margin-top: 8px; }
.wt-select { width: 100%; padding: 7px 10px; background: rgba(255,255,255,0.05); border: 1px solid var(--border-glass); border-radius: 6px; color: var(--text-primary); font-family: 'Inter', sans-serif; font-size: 12px; cursor: pointer; }
.wt-select option { background: #0f172a; }
.wt-obs-btn { width: 100%; padding: 8px 12px; background: rgba(6,182,212,0.15); border: 1px solid rgba(6,182,212,0.3); border-radius: 6px; color: #06b6d4; font-family: 'Inter', sans-serif; font-size: 12px; font-weight: 600; cursor: pointer; transition: all var(--transition-fast); margin-top: 10px; }
.wt-obs-btn:hover:not(:disabled) { background: rgba(6,182,212,0.25); }
.wt-obs-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.wt-obs-res { font-size: 12px; padding: 8px 10px; border-radius: 6px; line-height: 1.5; margin-top: 8px; }
.wt-obs-res.hidden { display: none; }
.wt-obs-ok { background: rgba(34,197,94,0.12); color: #4ade80; border: 1px solid rgba(34,197,94,0.25); }
.wt-obs-wrong { background: rgba(239,68,68,0.10); color: #f87171; border: 1px solid rgba(239,68,68,0.25); }
.wt-result-box { font-size: 13px; color: var(--text-secondary); line-height: 1.65; }
.wt-viva-btn { width: 100%; padding: 12px; background: linear-gradient(135deg, rgba(168,85,247,0.2), rgba(217,70,239,0.2)); border: 1px solid rgba(168,85,247,0.35); border-radius: var(--radius-sm); color: #d8b4fe; font-family: 'Inter', sans-serif; font-size: 13px; font-weight: 600; cursor: pointer; transition: all var(--transition-fast); }
.wt-viva-btn:hover { background: linear-gradient(135deg, rgba(168,85,247,0.3), rgba(217,70,239,0.3)); border-color: rgba(168,85,247,0.5); transform: translateY(-1px); }

.wt-viva-ov { position: fixed; inset: 0; z-index: 9999; display: flex; align-items: center; justify-content: center; background: rgba(0,0,0,0.75); backdrop-filter: blur(8px); padding: 20px; animation: psFadeSlide 0.25s ease; }
.wt-viva-ov.hidden { display: none; }
.wt-viva-modal { background: rgba(10,14,26,0.98); border: 1px solid var(--border-glass-hover); border-radius: var(--radius-lg); width: 100%; max-width: 560px; max-height: 88vh; overflow-y: auto; box-shadow: 0 24px 80px rgba(0,0,0,0.7); }
.wt-viva-hdr { display: flex; align-items: center; gap: 12px; padding: 18px 20px 14px; border-bottom: 1px solid var(--border-glass); }
.wt-viva-title { font-family: 'Space Grotesk', sans-serif; font-size: 17px; font-weight: 700; color: var(--text-primary); flex: 1; }
.wt-viva-score { font-size: 13px; color: var(--text-secondary); }
.wt-viva-close { width: 28px; height: 28px; border-radius: 50%; border: 1px solid var(--border-glass); background: transparent; color: var(--text-muted); cursor: pointer; font-size: 13px; transition: all 0.2s; display: flex; align-items: center; justify-content: center; }
.wt-viva-close:hover { background: rgba(239,68,68,0.15); color: #f87171; border-color: rgba(239,68,68,0.3); }
.wt-viva-pbar { height: 3px; background: rgba(255,255,255,0.06); }
.wt-viva-pfill { height: 100%; background: linear-gradient(90deg, #a855f7, #d946ef); transition: width 0.4s ease; }
.wt-viv-q { padding: 24px 20px; display: flex; flex-direction: column; gap: 14px; }
.wt-viv-num { font-size: 11px; font-weight: 600; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; }
.wt-viv-qtext { font-family: 'Space Grotesk', sans-serif; font-size: 16px; font-weight: 600; color: var(--text-primary); line-height: 1.5; }
.wt-viv-opts { display: flex; flex-direction: column; gap: 8px; }
.wt-vopt { padding: 12px 16px; background: rgba(255,255,255,0.04); border: 1px solid var(--border-glass); border-radius: 8px; color: var(--text-secondary); font-family: 'Inter', sans-serif; font-size: 13px; font-weight: 500; text-align: left; cursor: pointer; transition: all 0.2s; }
.wt-vopt:hover:not(:disabled) { background: rgba(168,85,247,0.12); border-color: rgba(168,85,247,0.3); color: var(--text-primary); }
.wt-vopt:disabled { cursor: not-allowed; }
.wt-vopt-ok { background: rgba(34,197,94,0.15) !important; border-color: rgba(34,197,94,0.45) !important; color: #4ade80 !important; }
.wt-vopt-bad { background: rgba(239,68,68,0.12) !important; border-color: rgba(239,68,68,0.4) !important; color: #f87171 !important; }
.wt-viv-exp { font-size: 13px; padding: 10px 14px; border-radius: 8px; line-height: 1.6; }
.wt-viv-exp.hidden { display: none; }
.wt-exp-ok { background: rgba(34,197,94,0.1); color: #86efac; border: 1px solid rgba(34,197,94,0.2); }
.wt-exp-bad { background: rgba(239,68,68,0.10); color: #fca5a5; border: 1px solid rgba(239,68,68,0.2); }
.wt-viv-sum { text-align: center; padding: 32px 24px; display: flex; flex-direction: column; align-items: center; gap: 8px; }
.wt-viv-grade { font-size: 32px; margin-bottom: 4px; }
.wt-viv-big { font-family: 'Space Grotesk', sans-serif; font-size: 48px; font-weight: 700; color: var(--text-primary); }
.wt-viv-pct { font-size: 16px; color: #a855f7; font-weight: 600; }

@media (max-width: 900px) {
  .wt-grid { grid-template-columns: 1fr; }
  .wt-sidebar { display: grid; grid-template-columns: repeat(3, 1fr); gap: 6px; }
  .wt-sidebar-hd, .wt-sidebar-note { grid-column: 1 / -1; }
  .wt-panel { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
}
@media (max-width: 600px) {
  .wt-sidebar { grid-template-columns: 1fr 1fr; }
  .wt-panel { grid-template-columns: 1fr; }
}

/* ============================================================
   BREAD MOLD FUNGUS (Microorganisms) — Experiment Styles
   ============================================================ */
.bm-root { display: flex; flex-direction: column; gap: 14px; padding: 4px 0; }
.bm-topbar { display: flex; align-items: center; gap: 16px; padding: 12px 16px; background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); flex-wrap: wrap; }
.bm-prog-wrap { flex: 1; display: flex; align-items: center; gap: 12px; min-width: 180px; }
.bm-prog-label { font-size: 12px; font-weight: 600; color: #eab308; font-family: 'JetBrains Mono', monospace; white-space: nowrap; }
.bm-prog-track { flex: 1; height: 6px; background: rgba(255,255,255,0.08); border-radius: 100px; overflow: hidden; }
.bm-prog-fill { height: 100%; background: linear-gradient(90deg, #eab308, #ca8a04); border-radius: 100px; transition: width 0.5s cubic-bezier(0.4,0,0.2,1); box-shadow: 0 0 8px rgba(234,179,8,0.4); }
.bm-top-btns { display: flex; gap: 8px; flex-wrap: wrap; }
.bm-btn { display: inline-flex; align-items: center; gap: 6px; padding: 7px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border-glass); background: rgba(255,255,255,0.05); color: var(--text-secondary); font-family: 'Inter', sans-serif; font-size: 12px; font-weight: 500; cursor: pointer; transition: all var(--transition-fast); }
.bm-btn:hover { background: rgba(255,255,255,0.1); color: var(--text-primary); border-color: var(--border-glass-hover); }
.bm-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.bm-btn-toggle.bm-btn-on { background: rgba(234,179,8,0.15); border-color: rgba(234,179,8,0.4); color: #fef08a; }
.bm-btn-demo { background: rgba(34,197,94,0.1); border-color: rgba(34,197,94,0.25); color: #4ade80; }
.bm-btn-demo:hover { background: rgba(34,197,94,0.2); border-color: rgba(34,197,94,0.5); }
.bm-btn-reset { background: rgba(239,68,68,0.08); border-color: rgba(239,68,68,0.2); color: #f87171; }
.bm-btn-reset:hover { background: rgba(239,68,68,0.15); border-color: rgba(239,68,68,0.4); }

.bm-grid { display: grid; grid-template-columns: 220px 1fr 240px; gap: 14px; min-height: 480px; }
.bm-sidebar { background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); padding: 14px 10px; display: flex; flex-direction: column; gap: 4px; }
.bm-sidebar-hd { font-size: 11px; font-weight: 600; text-transform: uppercase; letter-spacing: 1px; color: var(--text-muted); padding: 0 6px; margin-bottom: 8px; }
.bm-step { display: flex; align-items: flex-start; gap: 8px; padding: 9px 8px; border-radius: 8px; cursor: pointer; border: 1px solid transparent; transition: all var(--transition-fast); }
.bm-step:hover { background: rgba(255,255,255,0.04); border-color: var(--border-glass); }
.bm-s-ac { background: #eab3081a; border-color: #eab3084d; box-shadow: 0 0 12px #eab3081a; }
.bm-s-dn { background: #eab3080f; border-color: #eab30826; }
.bm-s-lk { opacity: 0.45; cursor: not-allowed; }
.bm-s-num { font-size: 10px; font-weight: 700; font-family: 'JetBrains Mono', monospace; color: var(--text-muted); min-width: 14px; padding-top: 1px; }
.bm-s-ac .bm-s-num, .bm-s-dn .bm-s-num { color: #eab308; }
.bm-s-ico { font-size: 16px; flex-shrink: 0; }
.bm-s-name { flex: 1; font-size: 12px; font-weight: 500; color: var(--text-secondary); line-height: 1.3; }
.bm-s-ac .bm-s-name { color: var(--text-primary); }
.bm-s-dn .bm-s-name { color: #fde047; }
.bm-s-chk { font-size: 13px; color: var(--text-muted); min-width: 16px; text-align: right; }
.bm-s-dn .bm-s-chk, .bm-s-ac .bm-s-chk { color: #eab308; }

.bm-sim-col { display: flex; flex-direction: column; gap: 10px; }
.bm-controls { display: flex; gap: 12px; flex-wrap: wrap; background: rgba(15,20,30,0.5); padding: 10px 14px; border-radius: var(--radius-sm); border: 1px solid var(--border-glass); }
.bm-control-group { display: flex; flex-direction: column; gap: 6px; border-right: 1px solid rgba(255,255,255,0.05); padding-right: 12px; }
.bm-control-group:last-child { border-right: none; padding-right: 0; }
.bm-ctrl-lbl { font-size: 10px; font-weight: 600; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.5px; }
.bm-chip-row { display: flex; gap: 6px; }
.bm-chip { padding: 4px 8px; font-size: 11px; background: rgba(255,255,255,0.05); border: 1px solid var(--border-glass); border-radius: 4px; cursor: pointer; transition: all 0.2s; color: var(--text-secondary); white-space: nowrap; }
.bm-chip:hover { background: rgba(255,255,255,0.1); color: var(--text-primary); }
.bm-chip.bm-chip-act { background: #eab30826; border-color: #eab30866; color: #fef08a; }
.bm-time-ctrls { display: flex; gap: 6px; align-items: center; }

.bm-canvas-wrap { position: relative; border-radius: var(--radius-md); overflow: hidden; border: 1px solid var(--border-glass); background: #060810; width: 100%; aspect-ratio: 560 / 380; }
.bm-canvas-wrap canvas { width: 100%; height: 100%; display: block; }
.bm-growth-meter { position: absolute; bottom: 10px; left: 10px; right: 10px; background: rgba(0,0,0,0.7); backdrop-filter: blur(4px); border: 1px solid var(--border-glass); padding: 8px 12px; border-radius: 6px; display: flex; align-items: center; gap: 10px; font-size: 11px; color: var(--text-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 1px; }
.bm-meter-bg { flex: 1; height: 6px; background: rgba(255,255,255,0.1); border-radius: 100px; }
.bm-meter-fill { height: 100%; width: 0%; background: linear-gradient(90deg, #22c55e, #ef4444); border-radius: 100px; transition: width 0.3s; }

.bm-overlay { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; background: rgba(6,8,16,0.82); backdrop-filter: blur(4px); z-index: 10; }
.bm-start-card { text-align: center; padding: 24px; background: rgba(15,20,30,0.9); border: 1px solid var(--border-glass); border-radius: 12px; box-shadow: 0 10px 40px rgba(0,0,0,0.5); max-width: 320px; }
.bm-big-btn { display: inline-block; padding: 10px 24px; background: linear-gradient(135deg, #ca8a04, #eab308); color: #fff; font-family: 'Inter', sans-serif; font-size: 14px; font-weight: 600; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: all var(--transition-fast); box-shadow: 0 4px 16px rgba(234,179,8,0.3); }
.bm-big-btn:hover { transform: translateY(-2px); box-shadow: 0 6px 24px rgba(234,179,8,0.45); }

.bm-desc-box { display: flex; align-items: flex-start; gap: 8px; padding: 10px 14px; background: rgba(15,20,30,0.5); border: 1px solid var(--border-glass); border-radius: var(--radius-sm); font-size: 13px; color: var(--text-secondary); line-height: 1.5; }
.bm-fb { padding: 8px 12px; border-radius: var(--radius-sm); font-size: 12px; font-weight: 500; animation: psFadeSlide 0.3s ease; }
.bm-fb.hidden { display: none; }
.bm-fb-success { background: rgba(34,197,94,0.15); border: 1px solid rgba(34,197,94,0.3); color: #4ade80; }
.bm-fb-error   { background: rgba(239,68,68,0.15);  border: 1px solid rgba(239,68,68,0.3);  color: #f87171; }

.bm-panel { display: flex; flex-direction: column; gap: 10px; overflow-y: auto; }
.bm-panel-sec { background: rgba(15,20,30,0.6); border: 1px solid var(--border-glass); border-radius: var(--radius-md); padding: 14px; }
.bm-panel-hd { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: #eab308; margin-bottom: 10px; border-bottom: 1px solid var(--border-glass); padding-bottom: 6px; }
.bm-stat-row { display: flex; justify-content: space-between; font-size: 12px; margin-bottom: 6px; }
.bm-stat-row span { color: var(--text-muted); }
.bm-form-lbl { font-size: 11px; color: var(--text-muted); display: block; margin-bottom: 4px; margin-top: 8px; }
.bm-select { width: 100%; padding: 7px 10px; background: rgba(255,255,255,0.05); border: 1px solid var(--border-glass); border-radius: 6px; color: var(--text-primary); }
.bm-select option { background: #0f172a; }
.bm-obs-btn { width: 100%; padding: 8px; background: rgba(234,179,8,0.15); border: 1px solid rgba(234,179,8,0.3); border-radius: 6px; color: #eab308; cursor: pointer; transition: 0.2s; margin-top: 10px; }
.bm-obs-btn:hover { background: rgba(234,179,8,0.25); }
.bm-viva-btn { width: 100%; padding: 10px; background: linear-gradient(135deg, #a855f733, #d946ef33); border: 1px solid #a855f755; border-radius: var(--radius-sm); color: #d8b4fe; font-weight: 600; cursor: pointer; transition: 0.2s; margin-top: 10px; }
.bm-viva-btn:hover { background: linear-gradient(135deg, #a855f74d, #d946ef4d); transform: translateY(-1px); }

.bm-viva-ov { position: fixed; inset: 0; z-index: 999; display: flex; align-items: center; justify-content: center; background: rgba(0,0,0,0.8); backdrop-filter: blur(4px); }
.bm-viva-ov.hidden { display: none; }
.bm-viva-mo { background: #0b0f19; border: 1px solid var(--border-glass-hover); border-radius: 12px; width: 100%; max-width: 500px; padding: 20px; box-shadow: 0 20px 60px rgba(0,0,0,0.6); }
.bm-viva-hd { display: flex; border-bottom: 1px solid var(--border-glass); padding-bottom: 12px; margin-bottom: 16px; align-items: center; }
.bm-vclose { background: transparent; border: none; color: var(--text-muted); cursor: pointer; font-size: 16px; }
.bm-vclose:hover { color: #f87171; }
.bm-vopt { display: block; width: 100%; text-align: left; padding: 10px 14px; background: rgba(255,255,255,0.05); border: 1px solid var(--border-glass); border-radius: 6px; color: var(--text-secondary); cursor: pointer; transition: 0.2s; }
.bm-vopt:hover:not(:disabled) { background: rgba(255,255,255,0.1); color: var(--text-primary); border-color: var(--border-glass-hover); }

@media (max-width: 900px) {
  .bm-grid { grid-template-columns: 1fr; }
  .bm-sidebar { display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px; }
  .bm-panel { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
}
@media (max-width: 600px) {
  .bm-sidebar { grid-template-columns: 1fr; }
  .bm-panel { grid-template-columns: 1fr; }
}

/* ============================================================
   LANDING HERO — Full-viewport welcome screen
   ============================================================ */
.landing-hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 100px 32px 80px;
  overflow: hidden;
  background: var(--bg-primary);
  transition: opacity 0.5s cubic-bezier(0.4, 0, 0.2, 1),
              max-height 0.5s cubic-bezier(0.4, 0, 0.2, 1) 0.3s,
              padding 0.5s cubic-bezier(0.4, 0, 0.2, 1) 0.3s,
              min-height 0.5s cubic-bezier(0.4, 0, 0.2, 1) 0.3s;
}

.landing-hero.landing-hero-dismissed {
  opacity: 0;
  min-height: 0;
  max-height: 0;
  padding: 0;
  pointer-events: none;
  overflow: hidden;
}

.landing-hero.landing-hero-hidden {
  display: none !important;
}

.landing-hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
}

/* Landing background glow removed */

.landing-grid-overlay {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 70% 60% at 50% 40%, black 20%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 40%, black 20%, transparent 75%);
}

.landing-hero-content {
  position: relative;
  z-index: 2;
  max-width: 720px;
  animation: landingContentIn 1s cubic-bezier(0.16, 1, 0.3, 1) both;
}

@keyframes landingContentIn {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.landing-badge {
  display: inline-block;
  padding: 7px 20px;
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.2);
  border-radius: 100px;
  font-size: 13px;
  color: var(--physics-primary);
  font-weight: 500;
  margin-bottom: 28px;
  letter-spacing: 0.3px;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  animation: landingBadgeIn 1s 0.2s cubic-bezier(0.16, 1, 0.3, 1) both;
}
@keyframes landingBadgeIn {
  from { opacity: 0; transform: translateY(12px) scale(0.95); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.landing-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(40px, 7vw, 72px);
  font-weight: 700;
  line-height: 1.05;
  color: var(--text-primary);
  margin-bottom: 24px;
  letter-spacing: -0.04em;
}

.landing-gradient {
  background: linear-gradient(180deg, #ffffff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.landing-desc {
  font-size: 17px;
  color: var(--text-secondary);
  line-height: 1.8;
  max-width: 580px;
  margin: 0 auto 40px;
  letter-spacing: 0;
}

.landing-cta-group {
  margin-bottom: 48px;
}

.landing-cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 18px 42px;
  background: linear-gradient(135deg, var(--physics-primary), var(--prelab-glow-2));
  color: #ffffff;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 17px;
  font-weight: 600;
  border: none;
  border-radius: 14px;
  cursor: pointer;
  transition: all var(--transition-smooth);
  box-shadow: 0 4px 24px var(--physics-glow), 0 0 0 0 var(--physics-bg);
  letter-spacing: -0.01em;
  position: relative;
  overflow: hidden;
}
.landing-cta-btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.15), transparent 60%);
  pointer-events: none;
}
.landing-cta-btn:hover {
  transform: translateY(-4px) scale(1.02);
  box-shadow: 0 12px 36px var(--physics-glow), 0 0 0 4px var(--physics-bg);
}
.landing-cta-btn:active {
  transform: translateY(-1px);
}

.landing-cta-arrow {
  font-size: 20px;
  transition: transform var(--transition-fast);
}
.landing-cta-btn:hover .landing-cta-arrow {
  transform: translateX(4px);
}

.landing-cta-sub {
  margin-top: 14px;
  font-size: 13px;
  color: var(--text-muted);
  letter-spacing: 0.3px;
}

.landing-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  animation: landingPillsIn 1s 0.6s cubic-bezier(0.16, 1, 0.3, 1) both;
}
@keyframes landingPillsIn {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

.landing-pill {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 14px;
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 100px;
  font-size: 13px;
  color: var(--text-secondary);
  font-weight: 500;
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  transition: all var(--transition-fast);
}
.landing-pill:hover {
  background: rgba(255,255,255,0.08);
  border-color: rgba(255,255,255,0.15);
  color: var(--text-primary);
  transform: translateY(-2px);
}

.landing-scroll-hint {
  position: absolute;
  bottom: 36px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
  letter-spacing: 1px;
  text-transform: uppercase;
  font-weight: 500;
  transition: opacity 0.5s ease;
  z-index: 2;
}

.landing-scroll-arrow {
  font-size: 18px;
  animation: scrollBounce 2s ease-in-out infinite;
}

@keyframes scrollBounce {
  0%, 100% { transform: translateY(0); opacity: 1; }
  50% { transform: translateY(8px); opacity: 0.5; }
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  border-top: 1px solid var(--border-glass);
  background: rgba(5, 7, 12, 0.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 48px 28px;
  text-align: center;
}

.footer-inner {
  max-width: var(--content-max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 4px;
}
.footer-logo {
  font-size: 22px;
}
.footer-name {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.footer-copy {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
}
.footer-sep {
  color: var(--text-muted);
}
.footer-link-item {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
  cursor: default;
}
.footer-link-item:hover {
  color: var(--text-primary);
}

/* ============================================================
   ███████╗ ██████╗██╗    ██████╗  █████╗ ██████╗
   ██╔════╝██╔════╝██║    ██╔══██╗██╔══██╗██╔══██╗
   ███████╗██║     ██║    ██║  ██║███████║██████╔╝
   ╚════██║██║     ██║    ██║  ██║██╔══██║██╔══██╗
   ███████║╚██████╗██║    ██████╔╝██║  ██║██████╔╝
   ╚══════╝ ╚═════╝╚═╝    ╚═════╝ ╚═╝  ╚═╝╚═════╝
   Scientific Digital Lab — Design Enhancement Layer
   Pure additive CSS — zero existing rules overwritten
   ============================================================ */

/* ── 1. GRAPH-PAPER BACKGROUND ───────────────────────────────── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(255,255,255,0.028) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.028) 1px, transparent 1px),
    linear-gradient(rgba(255,255,255,0.010) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.010) 1px, transparent 1px);
  background-size: 80px 80px, 80px 80px, 20px 20px, 20px 20px;
  background-position: -1px -1px, -1px -1px, -1px -1px, -1px -1px;
  mask-image: radial-gradient(ellipse 120% 120% at 50% 0%, black 40%, transparent 100%);
  -webkit-mask-image: radial-gradient(ellipse 120% 120% at 50% 0%, black 40%, transparent 100%);
}

/* Light mode adjusts the grid opacity */
[data-theme="light"] body::before {
  background-image:
    linear-gradient(rgba(0,0,20,0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,20,0.06) 1px, transparent 1px),
    linear-gradient(rgba(0,0,20,0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,20,0.025) 1px, transparent 1px);
  background-size: 80px 80px, 80px 80px, 20px 20px, 20px 20px;
}

/* ── 2. ENHANCED ACCENT COLORS ───────────────────────────────── */
:root {
  /* New accent system — replaces flat color per-subject with richer palette */
  --accent-physics:   #3b82f6;
  --accent-physics-2: #60a5fa;
  --glow-physics:     rgba(59, 130, 246, 0.3);

  --accent-chem:      #a855f7;
  --accent-chem-2:    #c084fc;
  --glow-chem:        rgba(168, 85, 247, 0.3);

  --accent-bio:       #22c55e;
  --accent-bio-2:     #4ade80;
  --glow-bio:         rgba(34, 197, 94, 0.3);

  /* Surface tokens — used in new card upgrades */
  --surface-01: rgba(255,255,255,0.03);
  --surface-02: rgba(255,255,255,0.06);
  --surface-03: rgba(255,255,255,0.10);
}
[data-theme="light"] {
  --surface-01: rgba(0,0,0,0.025);
  --surface-02: rgba(0,0,0,0.05);
  --surface-03: rgba(0,0,0,0.09);
}

/* ── 3. CARD SYSTEM UPGRADES ─────────────────────────────────── */
/* Subject cards — enhanced glow on hover */
.subject-physics:hover {
  border-color: var(--physics-primary) !important;
  box-shadow: 0 8px 32px var(--physics-glow), 0 0 0 1px var(--physics-bg);
}
.subject-chemistry:hover {
  border-color: var(--chemistry-primary) !important;
  box-shadow: 0 8px 32px var(--chemistry-glow), 0 0 0 1px var(--chemistry-bg);
}
.subject-biology:hover {
  border-color: var(--biology-primary) !important;
  box-shadow: 0 8px 32px var(--biology-glow), 0 0 0 1px var(--biology-bg);
}

/* Experiment list items — subtle accent left-border on hover */
.exp-list-item {
  border-left: 3px solid transparent;
  transition: all var(--transition-smooth), border-left-color var(--transition-fast);
}
.exp-list-item:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

/* Experiment icon — crisp rounded square with colored BG */
.exp-item-icon {
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

/* Glass cards — slightly improved depth */
.glass-card {
  box-shadow: 0 2px 12px rgba(0,0,0,0.25), inset 0 1px 0 rgba(255,255,255,0.04);
}

/* ── 4. NAVBAR POLISH ────────────────────────────────────────── */
.navbar {
  border-bottom: 1px solid rgba(255,255,255,0.06) !important;
  box-shadow: 0 1px 24px rgba(0,0,0,0.25);
}

/* Subtle top accent line on the navbar */
.navbar::after {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg,
    transparent 0%,
    rgba(59,130,246,0.4) 30%,
    rgba(168,85,247,0.4) 60%,
    transparent 100%
  );
  pointer-events: none;
}

/* ── 5. BUTTON SYSTEM POLISH ─────────────────────────────────── */
.sim-btn {
  position: relative;
  overflow: hidden;
  letter-spacing: 0.01em;
}
/* Shimmer on hover */
.sim-btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(105deg, transparent 40%, rgba(255,255,255,0.07) 50%, transparent 60%);
  transform: translateX(-100%);
  transition: transform 0.45s ease;
  pointer-events: none;
}
.sim-btn:hover::after {
  transform: translateX(100%);
}

/* Primary button — sharper shine */
.sim-btn.btn-primary {
  box-shadow: 0 2px 10px rgba(59,130,246,0.25), inset 0 1px 0 rgba(255,255,255,0.15);
}
.sim-btn.btn-primary:hover {
  box-shadow: 0 6px 24px rgba(59,130,246,0.4), inset 0 1px 0 rgba(255,255,255,0.2);
}

/* Secondary button outline style */
.sim-btn.btn-secondary {
  border-color: rgba(255,255,255,0.15) !important;
}
[data-theme="light"] .sim-btn {
  background: rgba(0,0,0,0.04);
  color: var(--text-primary);
  border-color: rgba(0,0,0,0.12);
}
[data-theme="light"] .sim-btn:hover {
  background: rgba(0,0,0,0.08);
}

/* ── 6. LAB RECORD ENHANCED ──────────────────────────────────── */
.lab-record {
  position: relative;
  overflow: hidden;
}
.lab-record::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg,
    var(--physics-primary),
    #a855f7,
    var(--chemistry-primary)
  );
  opacity: 0.6;
  pointer-events: none;
}
.lab-record-item {
  transition: background var(--transition-fast), border-color var(--transition-fast);
  border-radius: var(--radius-sm);
}
.lab-record-item:hover {
  background: rgba(255,255,255,0.04) !important;
  border-color: var(--border-glass-hover) !important;
}

/* ── 7. SIM AREA — ENHANCED ──────────────────────────────────── */
.sim-area {
  position: relative;
  z-index: 1;
}

/* Subtle corner bracket decoration for sim container */
.sim-canvas-wrap::after {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
  border-radius: inherit;
  background: linear-gradient(135deg, rgba(255,255,255,0.04) 0%, transparent 50%);
}

/* ── 8. SECTION LABELS — MONOSPACE FEEL ──────────────────────── */
.section-label {
  font-family: 'JetBrains Mono', 'Space Grotesk', sans-serif;
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 24px;
}
.section-label::before {
  content: '//';
  color: var(--physics-primary);
  opacity: 0.5;
  font-size: 10px;
  font-weight: 700;
}

/* ── 9. HERO SECTION — ADDED DEPTH ──────────────────────────── */
.hero-badge {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  letter-spacing: 0.05em;
}

/* Stat bar — terminal style numbers */
.stat-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 24px;
}

/* ── 10. SUBJECT CARDS — ICON GLOW ───────────────────────────── */
.subject-physics .subject-icon-wrap {
  box-shadow: 0 0 20px rgba(59,130,246,0.2), inset 0 1px 0 rgba(255,255,255,0.08);
}
.subject-chemistry .subject-icon-wrap {
  box-shadow: 0 0 20px rgba(249,115,22,0.2), inset 0 1px 0 rgba(255,255,255,0.08);
}
.subject-biology .subject-icon-wrap {
  box-shadow: 0 0 20px rgba(34,197,94,0.2), inset 0 1px 0 rgba(255,255,255,0.08);
}

/* ── 11. EXPERIMENT TOPBAR — TAGS ────────────────────────────── */
.exp-subject-badge {
  font-family: 'JetBrains Mono', monospace;
  letter-spacing: 0.08em;
}

/* ── 12. CONTROL SLIDERS — LIGHT MODE ────────────────────────── */
[data-theme="light"] .sim-control-slider {
  background: rgba(0,0,0,0.1);
}
[data-theme="light"] .sim-data-bar-track {
  background: rgba(0,0,0,0.08);
}
[data-theme="light"] .sim-result-row {
  background: rgba(0,0,0,0.02);
  border-color: rgba(0,0,0,0.08);
}

/* ── 13. SUBJECT PAGE CARDS (SEO PAGES) ──────────────────────── */
/* The inline-styled anchor cards in physics/chemistry/biology.html */
[data-theme="light"] a[style*="rgba(255,255,255,0.03)"],
[data-theme="light"] a[style*="background:rgba(255,255,255,0.03)"] {
  background: rgba(0,0,0,0.03) !important;
  border-color: rgba(0,0,0,0.1) !important;
  color: var(--text-primary) !important;
}

/* ── 14. PROFILE / GAMIFICATION POLISH ───────────────────────── */
.profile-name { color: var(--text-primary) !important; }
.stat-box-val { font-family: 'JetBrains Mono', monospace; }

/* ── 15. FOOTER — ENHANCED ───────────────────────────────────── */
.site-footer {
  position: relative;
}
.site-footer::before {
  content: '';
  position: absolute;
  top: 0; left: 10%; right: 10%;
  height: 1px;
  background: linear-gradient(90deg,
    transparent,
    var(--border-glass-hover),
    transparent
  );
  pointer-events: none;
}
[data-theme="light"] .site-footer {
  background: rgba(240,244,249,0.9);
}

/* ── 16. FLOATING ELEMENT DEPTH ──────────────────────────────── */
/* Rank card — elevated glass look */
.rank-card {
  background: var(--bg-card) !important;
  box-shadow: 0 4px 24px rgba(0,0,0,0.2), inset 0 1px 0 rgba(255,255,255,0.05) !important;
}

/* ── 17. SMOOTH ANIMATION UPGRADES ──────────────────────────────*/
/* Lift animation for all interactive cards */
.subject-card,
.exp-list-item,
.glass-card,
.rank-card {
  will-change: transform;
}

/* ── 18. RESPONSIVE GRID ADJUSTMENT ─────────────────────────── */
@media (max-width: 768px) {
  body::before {
    background-size: 40px 40px, 40px 40px, 10px 10px, 10px 10px;
  }
}

/* ── 19. LIGHT MODE LANDING PAGE ─────────────────────────────── */
[data-theme="light"] .landing-hero {
  background: var(--bg-primary);
}
[data-theme="light"] .landing-pill {
  background: rgba(0,0,0,0.04);
  border-color: rgba(0,0,0,0.09);
}
[data-theme="light"] .landing-grid-overlay {
  background-image:
    linear-gradient(rgba(0,0,20,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,20,0.04) 1px, transparent 1px);
  background-size: 60px 60px;
}

/* ── 20. PAGE-LEVEL Z-INDEX GUARD ────────────────────────────── */
/* Ensure app content sits above body::before grid (navbar excluded — stays fixed on top) */
.main-container,
.landing-hero,
.site-footer {
  position: relative;
  z-index: 1;
}

.navbar {
  position: fixed !important;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10000 !important;
  overflow: visible !important;
}

.navbar-inner,
.nav-actions,
.auth-area,
.user-profile {
  overflow: visible;
}

/* ============================================================
   MOBILE NAVIGATION (Hamburger Menu)
   ============================================================ */

.nav-hamburger {
  display: none;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 8px;
  width: 40px;
  height: 40px;
  position: relative;
  z-index: 2002;
  margin-left: auto;
}

.nav-hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--text-primary);
  margin: 5px auto;
  transition: all var(--transition-fast);
  border-radius: 2px;
}

@media (max-width: 1100px) {
  .nav-hamburger {
    display: block;
  }
  
  .nav-menu {
    position: fixed;
    top: 60px;
    left: 0;
    width: 100%;
    background: rgba(12, 17, 28, 0.98);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    flex-direction: column;
    padding: 20px;
    gap: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
    border-bottom: 1px solid var(--border-glass);
    transition: all var(--transition-fast);
    transform: translateY(-150%);
    opacity: 0;
    pointer-events: none;
    z-index: 2001;
  }
  
  .nav-menu.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  
  .nav-menu-link {
    width: 100%;
    justify-content: center;
    padding: 12px;
    font-size: 15px;
  }
  
  .nav-menu-dropdown {
    width: 100%;
    text-align: center;
  }
  
  .nav-menu-panel {
    position: static;
    box-shadow: none;
    background: rgba(255,255,255,0.03);
    min-width: 100%;
    transform: none;
    opacity: 1;
    pointer-events: auto;
    display: none;
    margin-top: 10px;
  }
  
  .nav-menu-dropdown:hover .nav-menu-panel,
  .nav-menu-dropdown:focus-within .nav-menu-panel {
    display: block;
  }
  
  /* Keep nav actions visible or re-arrange them */
  .nav-actions {
    margin-right: 10px;
  }
  
  /* Animate hamburger into an X */
  .nav-hamburger.open span:nth-child(1),
  .nav-menu.open ~ .nav-hamburger span:nth-child(1),
  .navbar:has(.nav-menu.open) .nav-hamburger span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }
  .nav-hamburger.open span:nth-child(2),
  .navbar:has(.nav-menu.open) .nav-hamburger span:nth-child(2) {
    opacity: 0;
  }
  .nav-hamburger.open span:nth-child(3),
  .navbar:has(.nav-menu.open) .nav-hamburger span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }
}

/* ── Experiment explorer search ─────────────────────────────── */
.filter-search-field {
  min-width: min(100%, 320px);
  flex: 1 1 320px;
}

.filter-search-input {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-primary);
  padding: 10px 14px;
  font: inherit;
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast), background var(--transition-fast);
}

.filter-search-input::placeholder {
  color: var(--text-muted);
}

.filter-search-input:focus {
  border-color: var(--physics-primary);
  background: rgba(255, 255, 255, 0.09);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.18);
}

[data-theme="light"] .filter-search-input {
  background: rgba(0, 0, 0, 0.035);
}

/* ============================================================
   AUTH SYSTEM
   ============================================================ */

.auth-area {
  display: flex;
  align-items: center;
  gap: 12px;
}

.nav-auth-btn {
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: #fff;
  padding: 10px 24px;
  border-radius: 50px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid rgba(59, 130, 246, 0.4);
  box-shadow: 0 0 10px rgba(59, 130, 246, 0.2), inset 0 0 10px rgba(139, 92, 246, 0.1);
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  white-space: nowrap;
  flex-shrink: 0;
}

.nav-auth-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(59, 130, 246, 0.8);
  box-shadow: 0 0 20px rgba(59, 130, 246, 0.5), inset 0 0 15px rgba(139, 92, 246, 0.3);
  transform: scale(1.05);
}

.user-profile {
  position: relative;
}

.profile-trigger {
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  padding: 6px 16px 6px 6px;
  border-radius: 50px;
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  transition: all 0.3s ease;
}

.profile-trigger:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(59, 130, 246, 0.4);
  box-shadow: 0 0 15px rgba(59, 130, 246, 0.2);
}

.user-avatar-glow {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--bg-card);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid rgba(59, 130, 246, 0.8);
  box-shadow: 0 0 10px rgba(59, 130, 246, 0.5);
  position: relative;
}

.user-avatar-glow::before {
  content: '';
  position: absolute;
  top: -4px; right: -4px; bottom: -4px; left: -4px;
  border-radius: 50%;
  border: 1px solid rgba(139, 92, 246, 0.5);
  animation: pulse-ring 2s infinite cubic-bezier(0.215, 0.61, 0.355, 1);
}

@keyframes pulse-ring {
  0% { transform: scale(0.8); opacity: 0.5; }
  100% { transform: scale(1.3); opacity: 0; }
}

#user-avatar-letter {
  font-weight: 700;
  font-size: 16px;
  color: #fff;
  font-family: 'Space Grotesk', sans-serif;
}

#username-display {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 14px;
  max-width: 140px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

@media (min-width: 1200px) {
  #username-display {
    max-width: 200px;
  }
}

.dropdown-arrow {
  color: var(--text-secondary);
  font-size: 12px;
  transition: transform 0.3s ease;
}

.profile-trigger.open .dropdown-arrow {
  transform: rotate(180deg);
}

.profile-trigger.open {
  border-color: rgba(59, 130, 246, 0.5);
  background: rgba(59, 130, 246, 0.12);
}

.profile-dropdown {
  position: fixed;
  top: 72px;
  right: 16px;
  min-width: 260px;
  max-width: min(320px, calc(100vw - 24px));
  background: rgba(15, 23, 42, 0.98);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(59, 130, 246, 0.45);
  border-radius: var(--radius-lg);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.65), 0 0 30px rgba(59, 130, 246, 0.2);
  padding: 8px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px) scale(0.98);
  transform-origin: top right;
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
  z-index: 10001;
  pointer-events: none;
}

.profile-dropdown.open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.profile-dropdown-header {
  padding: 10px 12px 12px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  margin-bottom: 4px;
}

.profile-dropdown-label {
  display: block;
  font-size: 10px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.profile-dropdown-email {
  display: block;
  font-size: 12px;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-primary);
  word-break: break-all;
  line-height: 1.4;
}

.profile-dropdown-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 10px 12px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  background: transparent;
  border: none;
  text-align: left;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease;
}

.profile-dropdown-item-icon {
  width: 20px;
  text-align: center;
  flex-shrink: 0;
  font-size: 15px;
}

.profile-dropdown-item:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.08);
}

.profile-dropdown-logout {
  margin-top: 4px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  color: #f87171;
}

.profile-dropdown-logout:hover:not(:disabled) {
  background: rgba(239, 68, 68, 0.15);
  color: #fca5a5;
}

.profile-dropdown-logout:disabled {
  opacity: 0.7;
  cursor: wait;
}

.auth-main {
  position: relative;
  min-height: calc(100vh - 72px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.auth-container {
  width: 100%;
  max-width: 420px;
  z-index: 10;
}

.auth-card {
  padding: 40px;
  border-radius: var(--radius-xl);
}

.auth-header {
  text-align: center;
  margin-bottom: 32px;
}

.auth-logo {
  font-size: 42px;
  margin-bottom: 16px;
  line-height: 1;
}

.auth-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 8px;
}

.auth-subtitle {
  color: var(--text-secondary);
  font-size: 14px;
}

.auth-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.input-group label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
}

.auth-input {
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border-glass);
  padding: 14px 16px;
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: 'JetBrains Mono', monospace;
  font-size: 14px;
  transition: var(--transition-fast);
}

.auth-input:focus {
  outline: none;
  border-color: var(--physics-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.auth-actions {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 8px;
}

.auth-btn {
  padding: 14px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: var(--transition-smooth);
  border: none;
}

.auth-btn:disabled, .auth-btn.loading {
  opacity: 0.6;
  cursor: not-allowed;
}

.auth-btn-primary {
  background: linear-gradient(135deg, var(--physics-primary), #8b5cf6);
  color: white;
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.auth-btn-primary:hover:not(:disabled) {
  box-shadow: 0 8px 24px rgba(59, 130, 246, 0.5);
  transform: translateY(-2px);
}

.auth-btn-secondary {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-glass);
}

.auth-btn-secondary:hover:not(:disabled) {
  background: var(--bg-card-hover);
}

.auth-divider {
  display: flex;
  align-items: center;
  text-align: center;
  color: var(--text-muted);
  font-size: 13px;
}

.auth-divider::before, .auth-divider::after {
  content: '';
  flex: 1;
  border-bottom: 1px solid var(--border-glass);
}

.auth-divider span {
  padding: 0 10px;
}

.auth-message {
  font-size: 13px;
  text-align: center;
  min-height: 20px;
}

.auth-message.error {
  color: #ef4444;
}

.auth-message.success {
  color: #10b981;
}

.hidden {
  display: none !important;
}

/* ── Auth page redesign ─────────────────────────────────────── */
.auth-page .auth-page-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}

.auth-shell {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 420px;
  gap: 28px;
  align-items: stretch;
}

.auth-showcase {
  padding: 40px 36px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  border-top: 3px solid var(--physics-primary);
}

.auth-showcase-badge {
  display: inline-flex;
  align-self: flex-start;
  padding: 6px 14px;
  border-radius: 100px;
  font-size: 12px;
  font-weight: 600;
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.25);
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.auth-showcase-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(28px, 4vw, 38px);
  font-weight: 700;
  line-height: 1.15;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.auth-showcase-desc {
  color: var(--text-secondary);
  line-height: 1.7;
  font-size: 15px;
  margin-bottom: 28px;
}

.auth-benefits {
  list-style: none;
  padding: 0;
  margin: 0 0 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.auth-benefits li {
  display: flex;
  gap: 14px;
  align-items: flex-start;
}

.auth-benefit-icon {
  font-size: 22px;
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.04);
  border-radius: 10px;
  border: 1px solid var(--border-glass);
}

.auth-benefits strong {
  display: block;
  font-size: 14px;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.auth-benefits span {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.auth-showcase-footnote {
  font-size: 12px;
  color: var(--text-muted);
  margin: 0;
}

.auth-card-v2 {
  padding: 32px 28px 28px;
  border-top: 3px solid #8b5cf6;
}

.auth-card-top {
  text-align: center;
  margin-bottom: 24px;
}

.auth-logo-ring {
  width: 56px;
  height: 56px;
  margin: 0 auto 14px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  background: rgba(59, 130, 246, 0.12);
  border: 1px solid rgba(59, 130, 246, 0.3);
  box-shadow: 0 0 24px rgba(59, 130, 246, 0.15);
}

.auth-card-heading {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 24px;
  font-weight: 700;
  margin: 0 0 6px;
  color: var(--text-primary);
}

.auth-card-sub {
  font-size: 14px;
  color: var(--text-secondary);
  margin: 0;
}

.auth-tabs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  padding: 4px;
  background: rgba(0, 0, 0, 0.25);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-glass);
  margin-bottom: 22px;
}

.auth-tab {
  padding: 10px 12px;
  border: none;
  border-radius: calc(var(--radius-md) - 2px);
  background: transparent;
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
  transition: var(--transition-fast);
}

.auth-tab.active {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.35), rgba(139, 92, 246, 0.25));
  color: var(--text-primary);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.auth-form-v2 {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.input-label-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.auth-text-btn {
  background: none;
  border: none;
  color: var(--physics-primary);
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  padding: 0;
}

.auth-text-btn:hover {
  text-decoration: underline;
}

.auth-submit-btn {
  width: 100%;
}

.auth-footer-note {
  text-align: center;
  margin: 20px 0 0;
  font-size: 13px;
}

.auth-skip-link {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s;
}

.auth-skip-link:hover {
  color: var(--physics-primary);
}

@media (max-width: 900px) {
  .auth-shell {
    grid-template-columns: 1fr;
    max-width: 440px;
  }

  .auth-showcase {
    padding: 28px 24px;
  }

  .auth-benefits {
    gap: 12px;
  }
}

/* ── Profile page redesign ──────────────────────────────────── */
.profile-page {
  max-width: 1100px;
  margin: 0 auto;
  padding-bottom: 48px;
}

.profile-page-toolbar {
  margin-bottom: 24px;
}

.profile-page-body {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.profile-hero-v2 {
  padding: 28px 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
  border-top: 3px solid var(--physics-primary);
}

.profile-hero-main {
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.profile-avatar-v2 {
  width: 88px;
  height: 88px;
  border-radius: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 700;
  flex-shrink: 0;
}

.profile-hero-label {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-muted);
  margin: 0 0 6px;
}

.profile-hero-name {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(26px, 4vw, 34px);
  font-weight: 700;
  margin: 0 0 6px;
  color: var(--text-primary);
}

.profile-hero-rank {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 18px;
  font-weight: 600;
  margin: 0;
}

.profile-account-pill,
.profile-guest-banner {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 14px 18px;
  flex-wrap: wrap;
}

.profile-account-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #10b981;
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.6);
  flex-shrink: 0;
}

.profile-account-label {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-muted);
}

.profile-account-email {
  font-size: 14px;
  color: var(--text-primary);
  font-family: 'JetBrains Mono', monospace;
}

.profile-signout-btn {
  margin-left: auto;
  padding: 8px 16px;
  border-radius: 100px;
  border: 1px solid rgba(239, 68, 68, 0.4);
  background: rgba(239, 68, 68, 0.1);
  color: #f87171;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
}

.profile-signout-btn:hover {
  background: rgba(239, 68, 68, 0.2);
}

.profile-guest-banner h3 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 16px;
  margin: 0 0 4px;
  color: var(--text-primary);
}

.profile-guest-banner p {
  margin: 0;
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.profile-cta-btn {
  margin-left: auto;
  padding: 10px 18px;
  border-radius: 100px;
  background: linear-gradient(135deg, var(--physics-primary), #8b5cf6);
  color: white;
  font-weight: 600;
  font-size: 13px;
  text-decoration: none;
  white-space: nowrap;
  transition: transform 0.2s, box-shadow 0.2s;
}

.profile-cta-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.35);
}

.profile-hero-progress-meta {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.profile-hero-track {
  height: 10px;
}

.profile-metrics {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.profile-metric {
  padding: 20px;
  text-align: center;
}

.profile-metric-label {
  display: block;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.profile-metric-value {
  font-family: 'JetBrains Mono', monospace;
  font-size: 28px;
  font-weight: 700;
}

.profile-metric-denom {
  font-size: 16px;
  color: var(--text-muted);
  font-weight: 500;
}

.profile-layout-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.profile-panel {
  padding: 24px;
}

.profile-panel-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 18px;
  font-weight: 700;
  margin: 0 0 18px;
  color: var(--text-primary);
}

.profile-rank-ladder {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.profile-rank-step {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-glass);
  background: rgba(255, 255, 255, 0.02);
}

.profile-rank-step.current {
  border-color: rgba(59, 130, 246, 0.45);
  background: rgba(59, 130, 246, 0.08);
}

.profile-rank-step.done {
  opacity: 0.85;
}

.profile-rank-step.locked {
  opacity: 0.45;
}

.profile-rank-step-icon {
  font-size: 22px;
  width: 36px;
  text-align: center;
}

.profile-rank-step-text {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.profile-rank-step-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
}

.profile-rank-step-xp {
  font-size: 11px;
  color: var(--text-muted);
}

.profile-rank-step-badge {
  font-size: 11px;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 100px;
  background: rgba(59, 130, 246, 0.2);
  color: var(--physics-primary);
}

.profile-progress-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.profile-progress-row {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-rows: auto auto;
  gap: 4px 12px;
  padding: 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-glass);
  text-decoration: none;
  color: inherit;
  transition: background 0.2s, border-color 0.2s;
}

.profile-progress-row:hover {
  background: rgba(255, 255, 255, 0.04);
  border-color: rgba(59, 130, 246, 0.3);
}

.profile-progress-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  grid-column: 1;
}

.profile-progress-pct {
  font-size: 12px;
  font-weight: 700;
  color: var(--physics-primary);
  font-family: 'JetBrains Mono', monospace;
}

.profile-progress-bar {
  grid-column: 1 / -1;
  height: 6px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 100px;
  overflow: hidden;
}

.profile-progress-bar span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--physics-primary), #8b5cf6);
  border-radius: 100px;
}

.profile-empty-note {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.6;
  margin: 0;
}

.profile-badges-grid {
  margin-bottom: 0;
}

.profile-badge-card-v2 {
  padding: 18px 12px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-glass);
  border-radius: 12px;
  text-align: center;
  transition: all 0.25s;
}

.profile-badge-card-v2.unlocked {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.18);
}

.profile-badge-card-v2.locked {
  opacity: 0.5;
}

.profile-badge-card-v2.locked .badge-icon {
  filter: grayscale(100%);
}

@media (max-width: 768px) {
  .profile-metrics {
    grid-template-columns: 1fr;
  }

  .profile-layout-grid {
    grid-template-columns: 1fr;
  }

  .profile-guest-banner,
  .profile-account-pill {
    flex-direction: column;
    align-items: flex-start;
  }

  .profile-cta-btn,
  .profile-signout-btn {
    margin-left: 0;
    width: 100%;
    text-align: center;
  }
}

/* ── Profile page v3 — account form + hero ──────────────────── */
.profile-loading {
  padding: 40px;
  text-align: center;
  color: var(--text-secondary);
}

.profile-hero-v3 {
  position: relative;
  overflow: hidden;
  padding: 32px 32px 28px;
  border-top: 3px solid var(--physics-primary);
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.profile-hero-glow {
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.9;
}

.profile-hero-v3 .profile-hero-main {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
}

.profile-avatar-v3 {
  width: 96px;
  height: 96px;
  border-radius: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 42px;
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 700;
}

.profile-hero-phone {
  margin: 8px 0 0;
  font-size: 14px;
  color: var(--text-secondary);
}

.profile-hero-text {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.profile-hero-progress {
  margin-top: 20px;
  width: 100%;
}

.profile-hero-rank-badge {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border-radius: 100px;
  border: 1px solid;
  font-size: 13px;
  font-weight: 600;
  background: rgba(0, 0, 0, 0.25);
}

.profile-hero-rank-icon {
  font-size: 18px;
}

.profile-section-label {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--text-muted);
  margin: 8px 0 0;
}

.profile-account-card {
  padding: 28px;
  border-top: 3px solid #8b5cf6;
}

.profile-account-card-head {
  margin-bottom: 22px;
}

.profile-account-card-head h2 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 22px;
  margin: 0 0 6px;
  color: var(--text-primary);
}

.profile-account-card-head p {
  margin: 0;
  font-size: 14px;
  color: var(--text-secondary);
}

.profile-account-form {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}

.profile-field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.profile-field label {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-muted);
}

.profile-input {
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  padding: 12px 14px;
  color: var(--text-primary);
  font-family: 'Inter', sans-serif;
  font-size: 15px;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.profile-input:focus {
  outline: none;
  border-color: rgba(59, 130, 246, 0.55);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.profile-input-readonly {
  opacity: 0.7;
  cursor: not-allowed;
}

.profile-form-message {
  grid-column: 1 / -1;
  font-size: 13px;
  min-height: 20px;
  text-align: center;
}

.profile-form-message.success {
  color: #10b981;
}

.profile-form-message.error {
  color: #f87171;
}

.profile-form-actions {
  grid-column: 1 / -1;
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.profile-save-btn {
  flex: 1;
  min-width: 140px;
  padding: 12px 24px;
  border: none;
  border-radius: 100px;
  background: linear-gradient(135deg, var(--physics-primary), #8b5cf6);
  color: white;
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

.profile-save-btn:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 8px 24px rgba(59, 130, 246, 0.35);
}

.profile-save-btn:disabled {
  opacity: 0.65;
  cursor: wait;
}

.profile-account-form .profile-signout-btn {
  margin-left: 0;
  flex: 0 1 auto;
}

.profile-guest-banner-v3 {
  padding: 28px;
  border-top: 3px solid var(--biology-primary);
  gap: 20px;
}

.profile-guest-icon {
  font-size: 40px;
}

.profile-metrics-v3 .profile-metric {
  position: relative;
  overflow: hidden;
}

.profile-metrics-v3 .profile-metric::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--physics-primary), transparent);
  opacity: 0.5;
}

.profile-layout-grid .profile-panel {
  min-height: 200px;
}

@media (max-width: 768px) {
  .profile-account-form {
    grid-template-columns: 1fr;
  }

  .profile-hero-rank-badge {
    margin-left: 0;
    width: 100%;
    justify-content: center;
  }

  .profile-form-actions {
    flex-direction: column;
  }

  .profile-save-btn,
  .profile-account-form .profile-signout-btn {
    width: 100%;
  }
}

/* ============================================================
   SHARED INTERACTIVE BOTTOM LAB RECORD TABS
   ============================================================ */
.bottom-card {
  margin-top: 30px;
  background: var(--bg-card, rgba(255,255,255,0.02));
  border: 1px solid var(--border-glass, rgba(255,255,255,0.05));
  border-radius: var(--radius-lg, 12px);
  padding: 24px;
  box-shadow: var(--shadow-lg, 0 8px 32px rgba(0,0,0,0.3));
}
.bottom-tabs {
  display: flex;
  border-bottom: 1px solid rgba(255,255,255,0.08);
  overflow-x: auto;
  gap: 8px;
  margin-bottom: 20px;
}
.bottom-tab {
  padding: 12px 24px;
  border: none;
  background: transparent;
  color: var(--text-secondary, #94a3b8);
  font-weight: 600;
  font-family: 'Space Grotesk', sans-serif;
  font-size: 14px;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all 0.25s ease;
  white-space: nowrap;
}
.bottom-tab:hover {
  color: var(--text-primary, #fff);
  background: rgba(255, 255, 255, 0.02);
}
.bottom-tab.active {
  color: #3b82f6;
  border-bottom-color: #3b82f6;
  background: rgba(59, 130, 246, 0.04);
}
.bottom-tab-body {
  display: none;
  line-height: 1.7;
  font-size: 14px;
  color: var(--text-secondary, #cbd5e1);
  animation: tabFadeIn 0.3s ease;
}
.bottom-tab-body.active {
  display: block;
}
.bottom-tab-body h5 {
  margin-top: 0;
  margin-bottom: 12px;
  font-size: 17px;
  font-family: 'Space Grotesk', sans-serif;
  color: var(--text-primary, #f1f5f9);
}

@keyframes tabFadeIn {
  from { opacity: 0; transform: translateY(5px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Observations Ledger Table */
.record-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  margin-top: 10px;
}
.record-table th, .record-table td {
  padding: 12px 14px;
  border: 1px solid rgba(255,255,255,0.06);
  text-align: center;
}
.record-table th {
  background: rgba(255,255,255,0.03);
  color: var(--text-muted, #94a3b8);
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 600;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.record-table td {
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-primary, #f1f5f9);
}

/* Dynamic Interactive Viva & MCQ */
.viva-widget {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 650px;
  background: rgba(0,0,0,0.15);
  border: 1px solid rgba(255,255,255,0.05);
  border-radius: 8px;
  padding: 24px;
}
.viva-qtext {
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 600;
  color: var(--text-primary, #f1f5f9);
  font-size: 16px;
  line-height: 1.5;
}
.viva-option-btn {
  width: 100%;
  text-align: left;
  padding: 12px 18px;
  background: rgba(255,255,255,0.02);
  border: 1px solid rgba(255,255,255,0.07);
  border-radius: 8px;
  color: var(--text-secondary, #cbd5e1);
  cursor: pointer;
  font-size: 13.5px;
  transition: all 0.2s ease;
}
.viva-option-btn:hover:not(:disabled) {
  background: rgba(255,255,255,0.06);
  border-color: rgba(255,255,255,0.18);
  transform: translateY(-1px);
}
.viva-option-btn.correct {
  background: rgba(16, 185, 129, 0.1) !important;
  border-color: #10b981 !important;
  color: #34d399 !important;
  font-weight: 600;
}
.viva-option-btn.incorrect {
  background: rgba(239, 68, 68, 0.1) !important;
  border-color: #ef4444 !important;
  color: #f87171 !important;
  font-weight: 600;
}
.viva-exp {
  padding: 12px 16px;
  background: rgba(255,255,255,0.03);
  border-left: 3px solid #3b82f6;
  border-radius: 4px;
  font-size: 13.5px;
  color: var(--text-secondary, #94a3b8);
  line-height: 1.5;
  margin-top: 10px;
}

/* Viva Flashcards (short Q&A format) */
.viva-flashcards {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.viva-flashcard {
  background: rgba(255,255,255,0.01);
  border: 1px solid rgba(255,255,255,0.05);
  border-radius: 8px;
  padding: 16px;
  transition: background 0.2s;
}
.viva-flashcard:hover {
  background: rgba(255,255,255,0.03);
}
.viva-card-q {
  font-weight: 600;
  color: var(--text-primary, #f1f5f9);
  margin-bottom: 8px;
  font-family: 'Space Grotesk', sans-serif;
  display: flex;
  gap: 8px;
}
.viva-card-a {
  font-size: 13.5px;
  color: var(--text-secondary, #94a3b8);
  padding: 8px 12px;
  background: rgba(0,0,0,0.15);
  border-radius: 6px;
  border-left: 2px solid #a855f7;
  display: none;
  animation: tabFadeIn 0.3s ease;
}

/* Centralized Mathematical Formula Rendering Styles */
.formula-inline {
  display: inline-block;
  vertical-align: middle;
  color: var(--text-primary, #f0f2f5);
  font-family: 'KaTeX_Main', 'KaTeX_Math', 'Times New Roman', serif;
}
.formula-block {
  display: block;
  text-align: center;
  margin: 12px 0;
  color: #ffffff; /* Bright white formula text */
  font-family: 'KaTeX_Main', 'KaTeX_Math', 'Times New Roman', serif;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0;
}
.formula-card {
  background: rgba(255, 255, 255, 0.02);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 12px;
  padding: 20px 24px;
  margin: 16px 0;
  box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.4);
  position: relative;
  overflow: hidden;
  transition: transform 0.25s ease, border-color 0.25s ease;
}
.formula-card:hover {
  transform: translateY(-2px);
  border-color: rgba(255, 255, 255, 0.12);
}
.formula-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 12px;
  padding: 1px;
  background: linear-gradient(135deg, rgba(59,130,246,0.25), rgba(168,85,247,0.25), rgba(236,72,153,0.25));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}
.math-container {
  display: flex;
  flex-direction: column;
  gap: 12px;
  width: 100%;
  min-width: 0;
  max-width: 100%;
  contain: inline-size;
}

.formula-box {
  overflow-x: auto;
  overflow-y: hidden;
  white-space: nowrap;
  max-width: 100%;
  contain: inline-size;
}

.formula-block {
  width: 100%;
  max-width: 100%;
  contain: inline-size;
}

.formula-block math,
.formula-block .katex,
.formula-card math,
.formula-card .katex {
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
}

.formula-block .katex-html,
.formula-card .katex-html {
  max-width: 100%;
}

.formula-block .katex-mathml,
.formula-card .katex-mathml {
  max-width: 1px;
}

/* ============================================================
   RESPONSIVE HARDENING
   ============================================================ */
img,
svg,
video,
canvas {
  max-width: 100%;
}

button,
input,
select,
textarea {
  max-width: 100%;
}

.glass-card,
.subject-card,
.explore-exp-card,
.explore-hub-card,
.sim-controls,
.sim-results,
.sim-data-panel,
.sim-notebook,
.lab-record,
.bottom-card {
  min-width: 0;
}

.bottom-card,
.bottom-tabs {
  max-width: 100%;
  contain: inline-size;
}

@media (min-width: 700px) {
  .bottom-tabs {
    flex-wrap: wrap;
    overflow-x: visible;
  }
}

.navbar-inner {
  width: 100%;
  min-width: 0;
}

@media (max-width: 1100px) {
  .navbar-inner {
    gap: 10px;
  }

  .nav-brand {
    min-width: 0;
    flex: 0 1 auto;
  }

  .nav-title-group {
    min-width: 0;
  }

  .nav-title,
  .nav-subtitle {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .nav-menu {
    display: flex;
    max-height: calc(100svh - 64px);
    overflow-y: auto;
  }

  .nav-actions {
    display: flex !important;
    flex-direction: row !important;
    width: auto !important;
    margin-left: auto;
    margin-right: 8px;
    gap: 8px;
    flex-shrink: 0;
    padding-top: 0 !important;
    border-top: 0 !important;
  }

  .nav-time {
    display: none;
  }

  .nav-auth-btn {
    padding-inline: 14px;
  }

  #username-display,
  .dropdown-arrow {
    display: none;
  }

  .profile-trigger {
    padding: 5px;
  }
}

@media (min-width: 1101px) {
  .nav-hamburger {
    display: none !important;
  }

  .nav-menu {
    position: static !important;
    display: flex !important;
    width: auto !important;
    max-height: none !important;
    padding: 0 !important;
    gap: 6px !important;
    flex-direction: row !important;
    align-items: center !important;
    background: transparent !important;
    border: 0 !important;
    box-shadow: none !important;
    opacity: 1 !important;
    pointer-events: auto !important;
    transform: none !important;
    overflow: visible !important;
  }

  .nav-menu-link {
    width: auto !important;
    justify-content: flex-start !important;
    padding: 7px 10px !important;
    font-size: 13px !important;
  }

  .nav-menu-dropdown {
    width: auto !important;
    text-align: left !important;
  }

  .nav-menu-panel {
    position: absolute !important;
    min-width: 160px !important;
    transform: translateY(-6px) !important;
    opacity: 0 !important;
    pointer-events: none !important;
    display: block !important;
    margin-top: 0 !important;
  }

  .nav-menu-panel-wide {
    min-width: 210px !important;
  }

  .nav-menu-dropdown:hover .nav-menu-panel,
  .nav-menu-dropdown:focus-within .nav-menu-panel {
    opacity: 1 !important;
    transform: translateY(0) !important;
    pointer-events: auto !important;
  }

  .nav-actions {
    width: auto !important;
    flex-direction: row !important;
    align-items: center !important;
    margin-left: 0 !important;
    margin-right: 0 !important;
    padding-top: 0 !important;
    border-top: 0 !important;
  }

  .nav-actions > *,
  .lang-btn,
  .theme-toggle-btn,
  .auth-area {
    width: auto !important;
  }
}

@media (max-width: 1024px) {
  :root {
    --content-max-width: 100%;
    --section-gap: 48px;
  }

  .main-container {
    padding-inline: 22px;
  }

  .explore-hub-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .filter-panel {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .filter-search-field,
  .clear-filter-btn {
    grid-column: 1 / -1;
  }

  .featured-grid,
  .explore-exp-grid {
    grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  }

  .stats-bar {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
  }

  .stat-divider {
    display: none;
  }
}

@media (max-width: 768px) {
  html {
    text-size-adjust: 100%;
    -webkit-text-size-adjust: 100%;
  }

  body {
    font-size: 14px;
    letter-spacing: 0;
  }

  .navbar-inner {
    height: 60px;
    padding-inline: 12px;
  }

  .nav-logo {
    font-size: 22px;
  }

  .nav-title {
    font-size: 15px;
  }

  .nav-subtitle {
    display: none;
  }

  .nav-actions {
    gap: 6px;
  }

  .nav-actions,
  .nav-actions > *,
  .lang-picker,
  .auth-area {
    width: auto !important;
  }

  .lang-btn {
    min-height: 36px;
    padding-inline: 9px;
    width: auto !important;
  }

  .lang-btn span:first-of-type {
    display: none;
  }

  .theme-toggle-btn,
  .nav-hamburger {
    width: 36px;
    height: 36px;
  }

  .nav-menu {
    top: 60px;
    padding: 14px;
    gap: 8px;
  }

  .nav-menu-link {
    min-height: 42px;
  }

  .main-container {
    padding: 78px 14px 36px;
  }

  .landing-hero {
    min-height: 100svh;
    padding: 76px 16px 44px;
    align-items: flex-start;
  }

  .landing-hero-content {
    max-width: 100%;
  }

  .landing-title {
    font-size: clamp(42px, 17vw, 78px);
    line-height: 0.95;
  }

  .landing-desc,
  .hero-desc,
  .explore-page-hero p {
    max-width: 100%;
  }

  .landing-cta-group,
  .landing-cta-btn,
  .clear-filter-btn,
  .resume-btn {
    width: 100%;
  }

  .landing-cta-btn,
  .resume-btn {
    justify-content: center;
  }

  .landing-pills {
    align-items: flex-start;
  }

  .hero-section {
    padding-top: 24px;
  }

  .hero-title {
    font-size: clamp(30px, 11vw, 44px);
  }

  .subject-grid,
  .explore-hub-grid,
  .filter-panel,
  .featured-grid,
  .explore-exp-grid,
  .profile-layout-grid,
  .profile-metrics,
  .profile-account-form,
  .auth-shell {
    grid-template-columns: 1fr;
  }

  .subject-card,
  .explore-hub-card,
  .explore-exp-card,
  .filter-panel,
  .auth-card,
  .auth-card-v2,
  .auth-showcase,
  .profile-panel,
  .profile-account-card,
  .profile-hero-v2,
  .profile-hero-v3,
  .bottom-card {
    padding: 18px;
  }

  .section-heading-row,
  .profile-hero-main,
  .profile-hero-v3 .profile-hero-main,
  .profile-account-pill,
  .profile-guest-banner,
  .recent-activity-card,
  .exp-title-wrap,
  .subject-header-info {
    align-items: flex-start;
    flex-direction: column;
  }

  .exp-list-item {
    align-items: flex-start;
    padding: 16px;
  }

  .exp-item-arrow {
    align-self: flex-end;
  }

  .stats-bar {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    padding: 18px;
  }

  .sim-control-row,
  .sim-data-row,
  .sim-result-row {
    align-items: stretch;
    flex-direction: column;
    gap: 8px;
  }

  .sim-control-label,
  .sim-data-label,
  .sim-control-value,
  .sim-data-value {
    min-width: 0;
    width: 100%;
    text-align: left;
  }

  .sim-btn,
  .sim-btn-group .sim-btn {
    width: 100%;
    justify-content: center;
  }

  .sim-canvas-wrap {
    overflow-x: auto;
  }

  .sim-canvas-wrap canvas {
    min-width: 320px;
  }

  .bottom-tabs {
    width: 100%;
    max-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
    padding-bottom: 6px;
  }

  .bottom-tab {
    flex: 0 0 auto;
    padding-inline: 16px;
  }

  .record-table {
    display: block;
    overflow-x: auto;
    white-space: nowrap;
  }

  .viva-widget {
    max-width: none;
    padding: 18px;
  }

  .profile-hero-rank-badge,
  .profile-cta-btn,
  .profile-signout-btn,
  .profile-save-btn,
  .profile-account-form .profile-signout-btn {
    width: 100%;
    justify-content: center;
    text-align: center;
  }
}

@media (max-width: 520px) {
  :root {
    --radius-lg: 16px;
    --radius-xl: 20px;
  }

  .main-container {
    padding-inline: 12px;
  }

  .nav-brand {
    gap: 8px;
  }

  .nav-actions {
    gap: 4px;
  }

  .nav-actions,
  .nav-actions > *,
  .lang-picker,
  .auth-area {
    width: auto !important;
  }

  .nav-auth-btn {
    font-size: 0;
    width: 36px;
    height: 36px;
    padding: 0;
    border-radius: 50%;
  }

  .nav-auth-btn::before {
    content: 'Login';
    font-size: 11px;
  }

  .lang-dropdown {
    position: fixed;
    top: 64px;
    left: 12px;
    right: 12px;
    width: auto;
    transform: translateY(-6px) scale(0.97);
  }

  .lang-dropdown.open {
    transform: translateY(0) scale(1);
  }

  .landing-badge,
  .hero-badge {
    max-width: 100%;
    white-space: normal;
  }

  .landing-scroll-hint {
    display: none;
  }

  .subject-meta,
  .profile-hero-progress-meta,
  .rank-progress-labels {
    align-items: flex-start;
    flex-direction: column;
    gap: 6px;
  }

  .stats-bar {
    grid-template-columns: 1fr;
  }

  .explore-page-hero h1 {
    font-size: clamp(34px, 16vw, 52px);
  }

  .profile-dropdown {
    right: 12px;
    left: 12px;
    min-width: 0;
    width: auto;
  }

  .auth-main {
    padding: 12px;
  }

  .auth-card-v2,
  .auth-showcase,
  .profile-account-card,
  .profile-hero-v3 {
    padding: 16px;
  }

  .rankup-modal-content {
    min-width: 0;
    width: calc(100vw - 24px);
    padding: 28px 18px;
  }
}

/* ── Landing Hero Two-Column Layout ── */
.landing-hero-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
  max-width: var(--content-max-width);
  position: relative;
  z-index: 2;
  gap: 48px;
}

@media (min-width: 992px) {
  .landing-hero-inner {
    display: grid;
    grid-template-columns: 1.15fr 0.85fr;
    align-items: center;
    gap: 40px;
    text-align: left;
  }
  .landing-hero-content {
    text-align: left;
    align-items: flex-start;
    margin: 0;
    max-width: 640px;
  }
  .landing-desc {
    margin-left: 0;
    margin-right: 0;
  }
  .landing-cta-group {
    align-items: flex-start;
  }
  .landing-pills {
    justify-content: flex-start;
  }
}

/* ── Hero Visualization Styling ── */
.landing-hero-visual {
  position: relative;
  width: 100%;
  max-width: 480px;
  height: 400px;
  perspective: 1200px;
  transform-style: preserve-3d;
  margin-top: 20px;
}

@media (max-width: 991px) {
  .landing-hero-visual {
    max-width: 440px;
    height: 360px;
    margin-top: 40px;
  }
}

/* Glassmorphism Panel Base */
.hero-panel {
  position: absolute;
  border-radius: var(--radius-md);
  background: rgba(11, 16, 32, 0.78);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-glass);
  box-shadow: var(--shadow-md);
  transition: border-color var(--transition-smooth), transform 0.1s ease-out;
  transform-style: preserve-3d;
  will-change: transform;
}

.hero-panel:hover {
  border-color: var(--border-glass-hover);
}

/* 1. Workspace Main Console (Z = 0) */
.panel-main {
  width: 100%;
  height: 310px;
  top: 40px;
  left: 0;
  z-index: 10;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.panel-main-header {
  height: 34px;
  border-bottom: 1px solid var(--border-glass);
  display: flex;
  align-items: center;
  padding: 0 14px;
  background: rgba(255, 255, 255, 0.02);
  gap: 12px;
}

.window-dots {
  display: flex;
  gap: 6px;
}

.window-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.15);
}

.panel-main-header:hover .window-dot:nth-child(1) { background: #ef4444; }
.panel-main-header:hover .window-dot:nth-child(2) { background: #fbbf24; }
.panel-main-header:hover .window-dot:nth-child(3) { background: #22c55e; }

.window-title {
  font-size: 11px;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-muted);
  letter-spacing: 0.5px;
}

.panel-main-body {
  flex: 1;
  display: flex;
  min-height: 0;
}

.panel-main-sidebar {
  width: 120px;
  border-right: 1px solid var(--border-glass);
  padding: 14px 8px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: rgba(3, 4, 7, 0.25);
}

.sidebar-tab {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 11px;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 6px 10px;
  border-radius: 6px;
  transition: all var(--transition-fast);
}

.sidebar-tab.active {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-primary);
  border-left: 2px solid var(--physics-primary);
}

.sidebar-tab-chem.active {
  border-left-color: var(--chemistry-primary);
}

.sidebar-tab-bio.active {
  border-left-color: var(--biology-primary);
}

.panel-main-content {
  flex: 1;
  position: relative;
  overflow: hidden;
  background: radial-gradient(circle at center, rgba(168, 85, 247, 0.05) 0%, transparent 70%);
}

#hero-three-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}

.panel-main-footer {
  height: 28px;
  border-top: 1px solid var(--border-glass);
  background: rgba(3, 4, 7, 0.35);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 14px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  color: var(--text-muted);
}

.status-indicator {
  display: flex;
  align-items: center;
  gap: 6px;
}

.status-dot {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--biology-primary);
  box-shadow: 0 0 8px var(--biology-primary);
}

/* 2. Oscilloscope Waveform Panel (Z = 45, bottom left) */
.panel-wave {
  width: 190px;
  height: 120px;
  bottom: 15px;
  left: -20px;
  z-index: 12;
  border-color: rgba(59, 130, 246, 0.25);
  display: flex;
  flex-direction: column;
  padding: 12px;
}

.panel-label {
  font-size: 10px;
  font-family: 'Space Grotesk', sans-serif;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--physics-primary);
  font-weight: 700;
  margin-bottom: 6px;
}

.wave-canvas-wrap {
  flex: 1;
  position: relative;
}

.oscilloscope-svg {
  width: 100%;
  height: 100%;
}

.oscilloscope-path {
  fill: none;
  stroke: var(--physics-primary);
  stroke-width: 1.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.wave-stats {
  display: flex;
  justify-content: space-between;
  margin-top: 6px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 9px;
  color: var(--text-muted);
}

/* 3. Bio-Telemetry Analyzer Panel (Z = 75, top right) */
.panel-bio {
  width: 175px;
  height: 130px;
  top: 10px;
  right: -15px;
  z-index: 11;
  border-color: rgba(34, 197, 94, 0.25);
  padding: 12px;
  display: flex;
  flex-direction: column;
}

.panel-bio .panel-label {
  color: var(--biology-primary);
}

.bio-chart-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  margin-top: 6px;
}

.bio-chart-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.bio-chart-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 9px;
  color: var(--text-muted);
  width: 36px;
}

.bio-chart-bar-track {
  flex: 1;
  height: 6px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border-glass);
  border-radius: 3px;
  overflow: hidden;
}

.bio-chart-bar-fill {
  height: 100%;
  background: var(--biology-primary);
  border-radius: 3px;
}

.bio-marker-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: rgba(34, 197, 94, 0.08);
  border: 1px solid rgba(34, 197, 94, 0.15);
  border-radius: 4px;
  padding: 2px 6px;
  font-size: 8px;
  color: var(--biology-primary);
  font-family: 'JetBrains Mono', monospace;
  align-self: flex-start;
  margin-top: 6px;
}

/* 4. Variables Tuning HUD (Z = 110, bottom right) */
.panel-hud {
  width: 210px;
  height: 95px;
  bottom: 25px;
  right: -25px;
  z-index: 13;
  padding: 12px;
  border-color: rgba(255, 255, 255, 0.08);
}

.hud-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 5px;
}

.hud-title {
  font-size: 9px;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-secondary);
}

.hud-slider {
  flex: 1;
  height: 3px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 1.5px;
  margin: 0 12px;
  position: relative;
}

.hud-slider-fill {
  height: 100%;
  background: var(--text-secondary);
  border-radius: 1.5px;
}

.hud-slider-fill-physics { background: var(--physics-primary); }
.hud-slider-fill-chem { background: var(--chemistry-primary); }

.hud-val {
  font-size: 9px;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-primary);
  font-weight: 500;
  width: 36px;
  text-align: right;
}

/* 5. Analytical Grid Background (Z = -30) */
.panel-grid {
  width: 110%;
  height: 110%;
  top: -5%;
  left: -5%;
  z-index: 1;
  background: transparent;
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  border: none;
  box-shadow: none;
  opacity: 0.25;
  pointer-events: none;
}

.radial-grid-svg {
  width: 100%;
  height: 100%;
}

.radial-grid-circle {
  fill: none;
  stroke: var(--text-muted);
  stroke-width: 0.5;
  stroke-dasharray: 4 6;
}

.radial-grid-line {
  stroke: var(--text-muted);
  stroke-width: 0.5;
  stroke-opacity: 0.5;
}

/* ── PHASE 5: PREMIUM INTERACTION LAYER STYLING ── */

/* 1. Cursor Spotlight Effect (Cards & Content areas) */
.explore-exp-card, 
.subject-card, 
.explore-hub-card, 
.stats-bar,
.concept-category-card,
.why-card,
.stat-card,
.roadmap-node {
  position: relative;
}

.explore-exp-card::before, 
.subject-card::before, 
.explore-hub-card::before, 
.stats-bar::before,
.concept-category-card::before,
.why-card::before,
.stat-card::before,
.roadmap-node::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(
    180px circle at var(--mouse-x, 0px) var(--mouse-y, 0px),
    rgba(255, 255, 255, 0.035),
    transparent 65%
  );
  opacity: 0;
  transition: opacity 0.4s ease;
  pointer-events: none;
  z-index: 3;
}

.explore-exp-card:hover::before, 
.subject-card:hover::before, 
.explore-hub-card:hover::before, 
.stats-bar:hover::before,
.concept-category-card:hover::before,
.why-card:hover::before,
.stat-card:hover::before,
.roadmap-node:hover::before {
  opacity: 1;
}

/* 2. Glass Reflection Sweep (Sheen on Card Hover) */
.explore-exp-card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    105deg,
    transparent 35%,
    rgba(255, 255, 255, 0.015) 45%,
    rgba(255, 255, 255, 0.065) 50%,
    rgba(255, 255, 255, 0.015) 55%,
    transparent 65%
  );
  transform: scale(1.6) translate(-100%, -100%) rotate(-12deg);
  transition: transform 0.65s cubic-bezier(0.16, 1, 0.3, 1);
  pointer-events: none;
  z-index: 4;
}

.explore-exp-card:hover::after {
  transform: scale(1.6) translate(100%, 100%) rotate(-12deg);
}

/* 3. Progressive Scroll Reveals */
.reveal-element {
  opacity: 0;
  transform: translateY(18px) scale(0.995);
  transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
  will-change: opacity, transform;
}

.reveal-element.reveal-visible {
  opacity: 1;
  transform: translateY(0) scale(1);
}

/* 4. Telemetry Glow Pulse Animation (Biology reaction) */
.bio-active-pulse {
  animation: bioGlowPulse 2.5s infinite alternate;
  border-color: rgba(34, 197, 94, 0.5) !important;
}

@keyframes bioGlowPulse {
  0% { box-shadow: var(--shadow-md), 0 0 4px rgba(34, 197, 94, 0.1); }
  100% { box-shadow: var(--shadow-md), 0 0 15px rgba(34, 197, 94, 0.35); }
}

/* 5. Magnetic Component Easing Rules */
.landing-cta-btn,
.subject-card,
.nav-auth-btn,
.profile-save-btn,
.resume-btn,
.sim-btn {
  will-change: transform;
}

/* ── PHASE 6: PREMIUM EXPERIMENT CARD EXPERIENCE ── */

/* 1. Staggered Viewport Entrance Reveal */
.explore-exp-card {
  opacity: 1;
  transform: translateY(0);
  transition: transform 0.4s cubic-bezier(0.25, 1, 0.5, 1), 
              opacity 0.4s cubic-bezier(0.25, 1, 0.5, 1), 
              border-color var(--transition-fast), 
              background var(--transition-fast), 
              box-shadow var(--transition-fast);
}

.explore-exp-card.explore-exp-card-hidden {
  opacity: 0 !important;
  transform: translateY(12px) !important;
  pointer-events: none;
}

/* 2. Top Accent Borders based on Subject */
.explore-exp-details {
  border-top: 2px solid transparent;
  position: relative; /* Relative anchor for overlays */
  transition: border-color var(--transition-fast);
}

.exp-physics .explore-exp-details {
  border-top-color: var(--physics-primary);
}

.exp-chemistry .explore-exp-details {
  border-top-color: var(--chemistry-primary);
}

.exp-biology .explore-exp-details {
  border-top-color: var(--biology-primary);
}

/* 3. Static Meta Fading out */
.explore-exp-meta-static {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.3s cubic-bezier(0.25, 1, 0.5, 1), 
              transform 0.3s cubic-bezier(0.25, 1, 0.5, 1);
}

.explore-exp-card:hover .explore-exp-meta-static,
.explore-exp-card.card-tapped .explore-exp-meta-static {
  opacity: 0;
  transform: translateY(-8px);
  pointer-events: none;
}

/* 4. Static Meta default layout */
.explore-exp-meta-static {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: auto;
}

.explore-exp-meta-static span {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  border: 1px solid var(--border-glass);
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  font-size: 11px;
  font-weight: 700;
  padding: 4px 8px;
}

/* 5. Hover Revealed CTA */
.explore-exp-cta {
  position: absolute;
  bottom: 20px;
  left: 20px;
  right: 20px;
  opacity: 0;
  transform: translateY(8px);
  pointer-events: none;
  transition: opacity 0.3s cubic-bezier(0.25, 1, 0.5, 1), 
              transform 0.3s cubic-bezier(0.25, 1, 0.5, 1);
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--accent-primary);
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  z-index: 2;
}

.explore-exp-card:hover .explore-exp-cta,
.explore-exp-card.card-tapped .explore-exp-cta {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.explore-exp-card:hover .explore-exp-cta .cta-arrow,
.explore-exp-card.card-tapped .explore-exp-cta .cta-arrow {
  transform: translateX(2.5px);
}

/* ── HOME REDESIGN & SPACING SPAN ── */

.home-featured-section,
.home-learning-path-section,
.home-categories-section,
.home-why-section,
.home-stats-section {
  margin-bottom: 96px;
  width: 100%;
}

/* Section Header Typography Layout */
.home-section-header {
  margin-bottom: 32px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.home-section-header .section-label {
  font-family: monospace;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.5px;
  color: var(--text-muted);
}

.home-section-title {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(24px, 4vw, 36px);
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
  margin: 4px 0 8px;
}

.home-section-desc {
  max-width: 650px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-muted);
}

/* Card Difficulty Badges */
.diff-badge {
  font-size: 10px;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 100px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-left: auto;
}

.node-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 10px;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 100px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-top: auto;
  align-self: flex-start;
  white-space: nowrap;
}

.badge-beginner {
  background: rgba(34, 197, 94, 0.12);
  color: #86efac;
  border: 1px solid rgba(34, 197, 94, 0.2);
}

.badge-intermediate {
  background: rgba(245, 158, 11, 0.12);
  color: #fde047;
  border: 1px solid rgba(245, 158, 11, 0.2);
}

.badge-advanced {
  background: rgba(239, 68, 68, 0.12);
  color: #fca5a5;
  border: 1px solid rgba(239, 68, 68, 0.2);
}

/* Card Metadata Line */
.explore-exp-meta-line {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 11px;
  color: var(--text-muted);
  font-weight: 500;
  margin-top: 10px;
}

.explore-exp-meta-line .meta-sep {
  opacity: 0.4;
  font-size: 8px;
}

/* Card Progress Status Labels */
.card-progress-status {
  font-weight: 600;
  font-size: 11px;
}

.card-progress-status.status-completed {
  color: #86efac;
}

.card-progress-status.status-progress {
  color: #fde047;
}

.card-progress-status.status-new {
  color: var(--text-muted);
}

/* Card Progress Indicators */
.card-progress-container {
  margin-top: 14px;
  margin-bottom: 14px;
}

.card-progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.card-progress-bar {
  height: 4px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 2px;
  overflow: hidden;
}

.card-progress-fill {
  height: 100%;
  background: var(--accent-primary);
  border-radius: 2px;
  transition: width 0.4s ease;
}

/* 2. Learning Path tab bars */
.learning-path-tabs {
  display: flex;
  gap: 12px;
  margin-bottom: 36px;
  border-bottom: 1px solid var(--border-glass);
  padding-bottom: 12px;
}

.path-tab-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.path-tab-btn:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.03);
}

.path-tab-btn.active {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.06);
  border-color: var(--border-glass-hover);
}

.tab-icon {
  width: 16px;
  height: 16px;
}

/* Roadmap timeline container */
.roadmap-track {
  display: none;
}

.roadmap-track.active {
  display: block;
  animation: tabFadeIn 0.35s ease;
}

@keyframes tabFadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.roadmap-timeline {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  position: relative;
  padding: 24px 0;
}

.roadmap-timeline::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--border-glass);
  z-index: 1;
}

.roadmap-node {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  padding: 24px;
  position: relative;
  z-index: 2;
  transition: transform var(--transition-smooth), border-color var(--transition-fast), box-shadow var(--transition-fast);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  min-height: 190px;
}

#track-physics .roadmap-node:hover {
  border-color: var(--physics-primary);
  box-shadow: 0 8px 30px var(--physics-glow);
  transform: translateY(-6px);
}

#track-chemistry .roadmap-node:hover {
  border-color: var(--chemistry-primary);
  box-shadow: 0 8px 30px var(--chemistry-glow);
  transform: translateY(-6px);
}

#track-biology .roadmap-node:hover {
  border-color: var(--biology-primary);
  box-shadow: 0 8px 30px var(--biology-glow);
  transform: translateY(-6px);
}

#track-physics .node-step { color: var(--physics-primary); }
#track-chemistry .node-step { color: var(--chemistry-primary); }
#track-biology .node-step { color: var(--biology-primary); }

.node-step {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 24px;
  font-weight: 700;
  opacity: 0.8;
  margin-bottom: 12px;
}

.roadmap-node h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.roadmap-node p {
  font-size: 12px;
  line-height: 1.5;
  color: var(--text-muted);
  flex: 1;
}

/* Responsive Roadmap Timeline Stacking */
@media (max-width: 768px) {
  .roadmap-timeline {
    grid-template-columns: 1fr;
    gap: 20px;
    padding-left: 24px;
  }
  
  .roadmap-timeline::before {
    top: 0;
    bottom: 0;
    left: 10px;
    width: 2px;
    height: 100%;
    right: auto;
  }
  
  .roadmap-node {
    min-height: auto;
  }
}

/* 3. Concept Categories Grid */
.concept-categories-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

@media (max-width: 768px) {
  .concept-categories-grid {
    grid-template-columns: 1fr;
  }
}

.concept-category-card {
  display: flex;
  flex-direction: column;
  padding: 24px;
  text-decoration: none;
  color: inherit;
  transition: transform var(--transition-smooth), border-color var(--transition-fast), background var(--transition-fast);
}

.concept-category-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glass-hover);
  background: var(--bg-card-hover);
}

.concept-card-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.05);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  color: var(--text-secondary);
}

.concept-icon {
  width: 20px;
  height: 20px;
}

.concept-category-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.concept-category-card p {
  font-size: 13px;
  line-height: 1.5;
  color: var(--text-muted);
  flex: 1;
  margin-bottom: 16px;
}

.concept-card-link {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.concept-category-card:hover .concept-card-link {
  color: var(--text-primary);
}

/* 4. Why SchoolUp Lab? Grid */
.why-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

@media (max-width: 768px) {
  .why-grid {
    grid-template-columns: 1fr;
  }
}

.why-card {
  padding: 32px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: transform var(--transition-smooth), border-color var(--transition-fast);
}

.why-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glass-hover);
}

.why-card-icon-wrap {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.why-icon {
  width: 24px;
  height: 24px;
}

.why-card-icon-wrap.physics-accent {
  background: var(--physics-bg);
  color: var(--physics-primary);
}

.why-card-icon-wrap.chemistry-accent {
  background: var(--chemistry-bg);
  color: var(--chemistry-primary);
}

.why-card-icon-wrap.biology-accent {
  background: var(--biology-bg);
  color: var(--biology-primary);
}

.why-card h3 {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
}

.why-card p {
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-muted);
}

/* 5. Statistics Cards Grid (Stagger reveal-ready) */
.stats-cards-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 20px;
}

@media (max-width: 1024px) {
  .stats-cards-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 600px) {
  .stats-cards-grid {
    grid-template-columns: 1fr;
  }
}

.stat-card {
  padding: 32px 20px;
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  
  /* Stagger reveal initial hidden states */
  opacity: 0.1;
  transform: translateY(12px);
  transition: opacity 0.6s cubic-bezier(0.16, 1, 0.3, 1), transform 0.6s cubic-bezier(0.16, 1, 0.3, 1), border-color var(--transition-fast);
}

.stat-card.reveal-active {
  opacity: 1;
  transform: translateY(0);
}

.stat-card:hover {
  border-color: var(--border-glass-hover);
}

.stat-card .stat-num {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(32px, 5vw, 44px);
  font-weight: 700;
  line-height: 1.1;
  color: var(--text-primary);
}

.stat-card .stat-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}


/* ═══════════════════════════════════════════════════════════════
   SUBJECT EXPERIMENT GALLERY
   ═══════════════════════════════════════════════════════════════ */

/* 1. Hero */
/* Scoped Gallery Accent Variables based on subject */
.subject-gallery[data-subject="physics"] {
  --gallery-accent: var(--physics-primary);
  --gallery-accent-bg: rgba(59,130,246,0.08);
  --gallery-accent-glow: var(--physics-glow);
}

.subject-gallery[data-subject="chemistry"] {
  --gallery-accent: var(--chemistry-primary);
  --gallery-accent-bg: rgba(168,85,247,0.08);
  --gallery-accent-glow: var(--chemistry-glow);
}

.subject-gallery[data-subject="biology"] {
  --gallery-accent: var(--biology-primary);
  --gallery-accent-bg: rgba(34,197,94,0.08);
  --gallery-accent-glow: var(--biology-glow);
}

.subject-gallery-hero {
  position: relative;
  padding: 32px 0 28px;
  max-height: 250px;
  overflow: hidden;
  margin-bottom: 36px;
}

.subject-gallery-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 70% 100% at 15% 50%, var(--gallery-accent-bg, rgba(59,130,246,0.08)), transparent 70%);
  pointer-events: none;
}

.subject-gallery-hero::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--gallery-accent, var(--physics-primary)), transparent);
  opacity: 0.25;
}

.subject-gallery-hero .back-btn {
  display: inline-flex;
  text-decoration: none;
  margin-bottom: 16px;
  position: relative;
  z-index: 2;
}

.subject-gallery-hero-content {
  position: relative;
  z-index: 2;
}

.subject-gallery-hero-content .home-section-mono {
  color: var(--gallery-accent);
  margin-bottom: 6px;
}

.subject-gallery-hero-content h1 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: clamp(28px, 4vw, 38px);
  font-weight: 700;
  color: var(--text-primary);
  margin: 0 0 6px;
  line-height: 1.2;
}

.subject-gallery-hero-stats {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 8px;
  flex-wrap: wrap;
}

.subject-gallery-hero-desc {
  font-size: 15px;
  color: var(--text-secondary);
  margin: 0;
  font-weight: 500;
}

.subject-gallery-completion {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 600;
}

.subject-gallery-completion-bar {
  width: 80px;
  height: 4px;
  background: rgba(255,255,255,0.06);
  border-radius: 2px;
  overflow: hidden;
}

.subject-gallery-completion-fill {
  height: 100%;
  border-radius: 2px;
  background: var(--gallery-accent);
  transition: width 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.subject-gallery-hero-topics {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.subject-gallery-hero-topics span {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  padding: 3px 10px;
  border: 1px solid var(--border-glass);
  border-radius: 100px;
  letter-spacing: 0.3px;
}

/* 2. Controls Bar */
.subject-gallery-controls {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 28px;
}

.subject-gallery-controls-row {
  display: flex;
  align-items: center;
  gap: 12px;
}

.subject-gallery-search {
  position: relative;
  flex: 1;
  max-width: 420px;
}

.subject-gallery-search svg {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--text-muted);
  pointer-events: none;
}

.subject-gallery-search input {
  width: 100%;
  padding: 10px 14px 10px 40px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 13px;
  font-family: inherit;
  outline: none;
  transition: border-color var(--transition-fast);
}

.subject-gallery-search input:focus {
  border-color: var(--gallery-accent, var(--accent-primary));
}

.subject-gallery-search input::placeholder {
  color: var(--text-muted);
}

/* Sort Dropdown */
.subject-gallery-sort {
  position: relative;
}

.subject-gallery-sort select {
  appearance: none;
  padding: 10px 32px 10px 12px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 12px;
  font-family: inherit;
  font-weight: 500;
  cursor: pointer;
  outline: none;
  transition: border-color var(--transition-fast);
}

.subject-gallery-sort select:focus {
  border-color: var(--gallery-accent, var(--accent-primary));
}

.subject-gallery-sort::after {
  content: '';
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 5px solid var(--text-muted);
  pointer-events: none;
}

/* Filter Pills */
.subject-gallery-filters {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  align-items: center;
}

.gallery-filter-pill {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 6px 12px;
  border-radius: 100px;
  border: 1px solid var(--border-glass);
  background: transparent;
  color: var(--text-muted);
  font-size: 11px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.gallery-filter-pill:hover {
  border-color: var(--border-glass-hover);
  color: var(--text-secondary);
}

.gallery-filter-pill.active {
  background: var(--gallery-accent, var(--accent-primary));
  border-color: var(--gallery-accent, var(--accent-primary));
  color: #fff;
}

.gallery-filter-pill .pill-count {
  font-size: 10px;
  opacity: 0.7;
  font-weight: 500;
}

.gallery-filter-pill.active .pill-count {
  opacity: 0.85;
}

/* Filter Separator */
.gallery-filter-separator {
  width: 1px;
  height: 18px;
  background: var(--border-glass);
  margin: 0 4px;
}

/* 3. Results Area */
.subject-gallery-results {
  position: relative;
}

.subject-gallery-count {
  font-size: 12px;
  font-family: 'JetBrains Mono', monospace;
  color: var(--text-muted);
  margin-bottom: 16px;
  font-weight: 500;
}

/* 4. Recommended Section */
.subject-gallery-recommend {
  margin-top: 56px;
  padding-top: 40px;
  border-top: 1px solid var(--border-glass);
}

.recommend-header {
  margin-bottom: 20px;
}

.recommend-header .home-section-mono {
  color: var(--gallery-accent);
}

.recommend-header h2 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  margin: 4px 0 0;
}

.recommend-card-wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: stretch;
}

.recommend-reason {
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 24px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  min-height: 200px;
}

.recommend-reason-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--gallery-accent);
  margin-bottom: 12px;
}

.recommend-reason p {
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-secondary);
  margin: 0 0 16px;
}

.recommend-continue-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  background: var(--gallery-accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-size: 13px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  text-decoration: none;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  width: fit-content;
}

.recommend-continue-btn:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

/* 5. Responsive */
@media (max-width: 768px) {
  .subject-gallery-hero {
    padding: 32px 0 28px;
  }

  .subject-gallery-hero-content h1 {
    font-size: 24px;
  }

  .subject-gallery-controls-row {
    flex-direction: column;
    align-items: stretch;
  }

  .subject-gallery-search {
    max-width: 100%;
  }

  .subject-gallery-filters {
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 4px;
    -webkit-overflow-scrolling: touch;
  }

  .recommend-card-wrapper {
    grid-template-columns: 1fr;
  }
}

/* Noscript SEO fallback styles */
.gallery-noscript-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.gallery-noscript-list a {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-md);
  text-decoration: none;
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 500;
  transition: border-color var(--transition-fast);
}

.gallery-noscript-list a:hover {
  border-color: var(--border-glass-hover);
}

.gallery-noscript-list a span.noscript-arrow {
  margin-left: auto;
  color: var(--text-muted);
}