/* ============================================================
   PROXY — Design System
   Premium visual language: Apple + Linear + Nothing + Stripe
   ============================================================ */

/* ── Google Fonts Import ── */
@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&family=Instrument+Serif:ital@0;1&family=JetBrains+Mono:wght@300;400;500;600;700;800&family=Caveat:wght@400;700&family=Outfit:wght@300;400;500;600;700;800;900&display=swap');

/* ── Design Tokens ── */
:root, html.dark-theme {
  /* Colors — Premium Slate-Grey Dark Mode */
  --bg-primary: #18181b;
  --bg-secondary: #202024;
  --bg-warm: #121214;
  --bg-card: rgba(30, 30, 35, 0.65);
  --bg-card-hover: rgba(38, 38, 44, 0.8);

  /* Accent */
  --accent: #7c3aed;
  --accent-hover: #8b5cf6;
  --accent-soft: rgba(124, 58, 237, 0.12);
  --accent-glow: rgba(124, 58, 237, 0.18);
  --accent-gradient: linear-gradient(135deg, #7c3aed 0%, #3b82f6 100%);

  /* Text */
  --text-primary: #f4f4f5;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --text-inverse: #ffffff;

  /* Glass */
  --glass-bg: rgba(30, 30, 35, 0.55);
  --glass-bg-strong: rgba(38, 38, 44, 0.75);
  --glass-border: rgba(255, 255, 255, 0.08);
  --glass-border-subtle: rgba(255, 255, 255, 0.05);
  --glass-blur: 20px;

  /* Navbar */
  --navbar-height: 76px;
  --navbar-bg: rgba(24, 24, 27, 0.75);

  /* Component specific theme variables for dynamic switching */
  --input-bg: rgba(255, 255, 255, 0.04);
  --input-border: rgba(255, 255, 255, 0.08);
  --input-focus-bg: rgba(30, 30, 35, 0.9);
  --shortcut-bg: rgba(255, 255, 255, 0.06);
  --btn-secondary-hover-bg: rgba(255, 255, 255, 0.08);
  --loader-bg-stroke: rgba(255, 255, 255, 0.06);
  --scrollbar-thumb-bg: rgba(255, 255, 255, 0.08);
  --scrollbar-thumb-hover-bg: rgba(255, 255, 255, 0.15);
  --tab-count-bg: rgba(255, 255, 255, 0.04);
  --card-code-bg: rgba(255, 255, 255, 0.04);
  --shelf-row-border: rgba(255, 255, 255, 0.03);
  --shelf-row-after-bg: rgba(255, 255, 255, 0.04);
  --paper-sheet-bg: #1e1e2d;
  --paper-sheet-border: rgba(255, 255, 255, 0.06);
  --paper-sheet-grid: rgba(255, 255, 255, 0.02);
  --paper-sheet-text: var(--text-secondary);
  --paper-header-border: rgba(255, 255, 255, 0.08);
  --paper-meta-color: rgba(255, 255, 255, 0.35);
  --paper-body-line-bg: rgba(255, 255, 255, 0.05);
  --cube-front-bg-start: rgba(45, 45, 60, 0.85);
  --cube-front-bg-mid: rgba(35, 35, 50, 0.65);
  --cube-front-bg-end: rgba(25, 25, 38, 0.45);
  --cube-front-border: rgba(255, 255, 255, 0.08);
  --cube-front-shadow: rgba(255, 255, 255, 0.08);

  /* Shadows — Subtle on dark surfaces */
  --shadow-xs: 0 1px 3px rgba(0, 0, 0, 0.2);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.35);
  --shadow-xl: 0 30px 60px rgba(0, 0, 0, 0.4);
  --shadow-accent: 0 8px 24px rgba(124, 58, 237, 0.15);
  --shadow-cube: 0 20px 40px rgba(0, 0, 0, 0.3), 0 8px 16px rgba(0, 0, 0, 0.2);

  /* Borders */
  --border-radius-sm: 10px;
  --border-radius-md: 16px;
  --border-radius-lg: 24px;
  --border-radius-xl: 32px;
  --border-radius-full: 100px;

  /* Typography Design Tokens */
  --font-family-display: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-family-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-family-serif: 'Instrument Serif', Georgia, serif;
  --font-family-mono: 'JetBrains Mono', monospace;
  --font-family-hand: 'Caveat', cursive;

  /* Main Fallback Variable */
  --font-family: var(--font-family-sans);
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  --font-size-4xl: 2.5rem;
  --font-size-5xl: 3.5rem;
  --font-size-6xl: 4.5rem;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;
  --space-5xl: 8rem;

  /* Timing — Apple-grade easing */
  --ease-out: cubic-bezier(0.25, 1, 0.5, 1);
  --ease-spring: cubic-bezier(0.2, 0.8, 0.2, 1);
  --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
  --duration-fast: 0.15s;
  --duration-normal: 0.3s;
  --duration-slow: 0.6s;
  --duration-slower: 1s;

  /* Z-index layers */
  --z-bg: 0;
  --z-content: 1;
  --z-overlay: 50;
  --z-navbar: 90;
  --z-modal: 100;
  --z-loader: 200;
}

html.light-theme, body.light-mode {
  /* Colors — Original Light Theme */
  --bg-primary: #f4f4f9;
  --bg-secondary: #ffffff;
  --bg-warm: #faf9fb;
  --bg-card: rgba(255, 255, 255, 0.55);
  --bg-card-hover: rgba(255, 255, 255, 0.75);

  /* Accent */
  --accent: #7c3aed;
  --accent-hover: #6d28d9;
  --accent-soft: rgba(124, 58, 237, 0.08);
  --accent-glow: rgba(124, 58, 237, 0.12);
  --accent-gradient: linear-gradient(135deg, #7c3aed 0%, #3b82f6 100%);

  /* Text */
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-inverse: #ffffff;

  /* Glass */
  --glass-bg: rgba(255, 255, 255, 0.45);
  --glass-bg-strong: rgba(255, 255, 255, 0.65);
  --glass-border: rgba(255, 255, 255, 0.6);
  --glass-border-subtle: rgba(255, 255, 255, 0.35);

  /* Navbar */
  --navbar-bg: rgba(244, 244, 249, 0.6);

  /* Component specific theme variables for light theme */
  --input-bg: rgba(0, 0, 0, 0.03);
  --input-border: rgba(0, 0, 0, 0.05);
  --input-focus-bg: #ffffff;
  --shortcut-bg: rgba(0, 0, 0, 0.05);
  --btn-secondary-hover-bg: rgba(255, 255, 255, 0.6);
  --loader-bg-stroke: rgba(0, 0, 0, 0.03);
  --scrollbar-thumb-bg: rgba(0, 0, 0, 0.1);
  --scrollbar-thumb-hover-bg: rgba(0, 0, 0, 0.18);
  --tab-count-bg: rgba(0, 0, 0, 0.03);
  --card-code-bg: rgba(0, 0, 0, 0.03);
  --shelf-row-border: rgba(15, 23, 42, 0.04);
  --shelf-row-after-bg: rgba(255, 255, 255, 0.6);
  --paper-sheet-bg: #fdfbf7;
  --paper-sheet-border: rgba(0, 0, 0, 0.08);
  --paper-sheet-grid: rgba(0, 0, 0, 0.03);
  --paper-sheet-text: #334155;
  --paper-header-border: rgba(0, 0, 0, 0.1);
  --paper-meta-color: rgba(0, 0, 0, 0.5);
  --paper-body-line-bg: rgba(0, 0, 0, 0.06);
  --cube-front-bg-start: rgba(255, 255, 255, 0.85);
  --cube-front-bg-mid: rgba(245, 243, 255, 0.65);
  --cube-front-bg-end: rgba(237, 233, 254, 0.45);
  --cube-front-border: rgba(255, 255, 255, 0.8);
  --cube-front-shadow: rgba(255, 255, 255, 0.9);

  /* Shadows — Soft, volumetric */
  --shadow-xs: 0 1px 3px rgba(0, 0, 0, 0.03);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.08);
  --shadow-xl: 0 30px 60px rgba(0, 0, 0, 0.1);
  --shadow-accent: 0 8px 24px rgba(124, 58, 237, 0.12);
  --shadow-cube: 0 20px 40px rgba(0, 0, 0, 0.08), 0 8px 16px rgba(0, 0, 0, 0.04);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  width: 100%;
  min-height: 100vh;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-family-sans);
  font-size: var(--font-size-base);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Typography Overrides ── */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family-display);
  font-weight: 700;
  letter-spacing: -0.02em;
}

/* Elegant serif highlights */
.font-serif-italic {
  font-family: var(--font-family-serif);
  font-style: italic;
  font-weight: 400;
}

/* Technical monospaced text (numbers, parameters, buttons) */
.font-mono-tech {
  font-family: var(--font-family-mono);
  font-size: 0.9em;
  letter-spacing: -0.02em;
}

/* Handwritten callouts */
.font-handwritten {
  font-family: var(--font-family-hand);
  font-size: 1.25rem;
  line-weight: 1;
}

/* ── Background Glow Blurs ── */
.bg-glow {
  position: fixed;
  width: 800px;
  height: 800px;
  border-radius: 50%;
  filter: blur(160px);
  pointer-events: none;
  z-index: var(--z-bg);
  opacity: 0.3;
}

.bg-glow--purple {
  background: radial-gradient(circle, rgba(124, 58, 237, 0.15) 0%, transparent 70%);
  top: -20%;
  left: -10%;
}

.bg-glow--blue {
  background: radial-gradient(circle, rgba(59, 130, 246, 0.10) 0%, transparent 70%);
  bottom: -10%;
  right: -10%;
}

/* ── Glass Components ── */
.glass {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
}

.glass--strong {
  background: var(--glass-bg-strong);
}

/* ── Navbar ── */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--navbar-height);
  background: var(--navbar-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  z-index: var(--z-navbar);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 6%;
  transition: all var(--duration-normal) var(--ease-smooth);
}

.nav-left {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: inherit;
}

.logo-icon {
  width: 28px;
  height: 28px;
  fill: var(--accent);
  filter: drop-shadow(0 2px 8px var(--accent-glow));
}

.logo-text {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.logo-text span {
  color: #ef4444;
}

.nav-center {
  display: flex;
  align-items: center;
  gap: 2.2rem;
  list-style: none;
}

.nav-link {
  font-size: 0.925rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color var(--duration-fast) ease;
  cursor: pointer;
  position: relative;
}

.nav-link:hover,
.nav-link.active {
  color: var(--accent);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background-color: var(--accent);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

/* ── Search Input (Spotlight) ── */
.search-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.search-input {
  width: 180px;
  height: 38px;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  border-radius: var(--border-radius-sm);
  padding: 0 1rem 0 2.2rem;
  font-family: inherit;
  font-size: var(--font-size-sm);
  color: var(--text-primary);
  outline: none;
  transition: all var(--duration-normal) var(--ease-smooth);
}

.search-input:focus {
  width: 240px;
  background: var(--input-focus-bg);
  border-color: var(--accent);
  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.15);
}

.search-icon {
  position: absolute;
  left: 0.8rem;
  width: 14px;
  height: 14px;
  fill: var(--text-muted);
  pointer-events: none;
}

.search-shortcut {
  position: absolute;
  right: 0.8rem;
  font-size: 0.725rem;
  color: var(--text-muted);
  background: var(--shortcut-bg);
  padding: 2px 6px;
  border-radius: 6px;
  pointer-events: none;
}

/* ── Theme Toggle ── */
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-icon {
  width: 20px;
  height: 20px;
  fill: var(--text-muted);
  transition: fill var(--duration-fast) ease;
}

.theme-toggle:hover .theme-icon {
  fill: var(--accent);
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.85rem 1.8rem;
  border-radius: 14px;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
  border: none;
}

.btn--primary {
  background: var(--accent);
  color: var(--text-inverse);
  box-shadow: 0 6px 20px rgba(124, 58, 237, 0.2);
}

.btn--primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 10px 24px rgba(124, 58, 237, 0.3);
}

.btn--primary .arrow {
  transition: transform 0.25s ease;
}

.btn--primary:hover .arrow {
  transform: translateX(3px);
}

.btn--secondary {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.btn--secondary:hover {
  background: var(--btn-secondary-hover-bg);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn--secondary svg {
  width: 18px;
  height: 18px;
  fill: var(--text-primary);
}

.btn-signin {
  background: var(--accent);
  color: var(--text-inverse);
  border: none;
  padding: 0.6rem 1.4rem;
  border-radius: var(--border-radius-sm);
  font-family: inherit;
  font-size: var(--font-size-sm);
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.25s ease;
  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.15);
}

.btn-signin:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(124, 58, 237, 0.25);
}

/* ── Section Helpers ── */
.section-container {
  width: 100%;
  max-width: 1300px;
  margin: 0 auto;
  padding: 0 6%;
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: var(--space-2xl);
}

.section-header h2 {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.view-all {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--accent);
  text-decoration: none;
  transition: color var(--duration-fast) ease;
}

.view-all:hover {
  color: var(--accent-hover);
}

/* ── Global Utility ── */
.gradient-text {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.spine-badge {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-weight: 700;
  font-size: 0.6rem;
  letter-spacing: 0.08em;
  transform: rotate(180deg);
  text-transform: uppercase;
  background: rgba(255,255,255,0.15);
  padding: 4px 3px;
  border-radius: 4px;
  text-align: center;
  font-family: var(--font-family);
}

/* ── Glass Card (Reusable) ── */
.glass-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--border-radius-lg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  box-shadow: var(--shadow-md);
  padding: var(--space-xl);
  transition: all var(--duration-normal) var(--ease-out);
}

.glass-card:hover {
  background: var(--bg-card-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

/* ── Loading Overlay ── */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--bg-primary);
  z-index: var(--z-loader);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  transition: opacity 0.8s var(--ease-out), visibility 0.8s;
}

.loading-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  padding: var(--space-2xl);
  border-radius: var(--border-radius-lg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  display: flex;
  flex-direction: column;
  align-items: center;
  box-shadow: var(--shadow-lg);
  width: 320px;
}

.loader-ring {
  width: 80px;
  height: 80px;
  position: relative;
  margin-bottom: var(--space-lg);
}

.loader-ring-svg {
  transform: rotate(-90deg);
  width: 100%;
  height: 100%;
}

.loader-circle-bg {
  fill: none;
  stroke: var(--loader-bg-stroke);
  stroke-width: 4px;
}

.loader-circle-progress {
  fill: none;
  stroke: var(--accent);
  stroke-width: 4px;
  stroke-linecap: round;
  stroke-dasharray: 226;
  stroke-dashoffset: 226;
  transition: stroke-dashoffset 0.1s linear;
  filter: drop-shadow(0 2px 6px var(--accent-glow));
}

.loader-percentage {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--text-primary);
}

.loader-text {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* ── Scroll Indicator ── */
.scroll-indicator {
  position: fixed;
  bottom: 2.2rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.5s ease, visibility 0.5s ease;
  pointer-events: none;
}

.scroll-indicator.visible {
  opacity: 0.8;
  visibility: visible;
}

.mouse {
  width: 22px;
  height: 36px;
  border: 2px solid var(--text-primary);
  border-radius: 12px;
  position: relative;
  margin-bottom: var(--space-sm);
}

.wheel {
  width: 4px;
  height: 6px;
  background-color: var(--accent);
  border-radius: 2px;
  position: absolute;
  top: 6px;
  left: 50%;
  transform: translateX(-50%);
  animation: scrollWheel 1.8s infinite var(--ease-out);
}

@keyframes scrollWheel {
  0%   { top: 6px;  opacity: 0; }
  30%  { opacity: 1; }
  80%  { top: 20px; opacity: 0; }
  100% { top: 6px;  opacity: 0; }
}

.scroll-text {
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  font-weight: 600;
}

/* ── Scrollbar ── */
::-webkit-scrollbar {
  width: 6px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb-bg);
  border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--scrollbar-thumb-hover-bg);
}

/* ── Hyper-Realistic 3D Acrylic Cubes ── */

.cube-wrapper {
  perspective: 800px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.2rem;
  cursor: pointer;
  min-width: 130px;
}

.cube-scene {
  width: 100px;
  height: 100px;
  position: relative;
  transform-style: preserve-3d;
  transform: rotateX(-12deg) rotateY(22deg);
  transition: transform 0.6s var(--ease-spring);
}

/* Individual face materials with light direction simulation */
.cube-face {
  position: absolute;
  width: 100px;
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 20px;
  backface-visibility: hidden;
}

/* Front face — brightest, main content face */
.cube-face--front {
  transform: rotateY(0deg) translateZ(50px);
  background: linear-gradient(
    145deg,
    var(--cube-front-bg-start) 0%,
    var(--cube-front-bg-mid) 50%,
    var(--cube-front-bg-end) 100%
  );
  border: 1.5px solid var(--cube-front-border);
  box-shadow:
    inset 0 1px 0 var(--cube-front-shadow),
    inset 0 -2px 6px rgba(124, 58, 237, 0.06),
    0 0 0 0.5px rgba(255, 255, 255, 0.02);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

/* Back face */
.cube-face--back {
  transform: rotateY(180deg) translateZ(50px);
  background: linear-gradient(
    145deg,
    rgba(30, 30, 48, 0.5) 0%,
    rgba(22, 22, 38, 0.3) 100%
  );
  border: 1px solid rgba(255, 255, 255, 0.04);
}

/* Right face — lit side */
.cube-face--right {
  transform: rotateY(90deg) translateZ(50px);
  background: linear-gradient(
    180deg,
    rgba(35, 35, 55, 0.6) 0%,
    rgba(25, 25, 42, 0.35) 100%
  );
  border: 1px solid rgba(255, 255, 255, 0.06);
  box-shadow: inset -2px 0 8px rgba(124, 58, 237, 0.05);
}

/* Left face — shadow side */
.cube-face--left {
  transform: rotateY(-90deg) translateZ(50px);
  background: linear-gradient(
    180deg,
    rgba(25, 25, 42, 0.45) 0%,
    rgba(18, 18, 30, 0.25) 100%
  );
  border: 1px solid rgba(255, 255, 255, 0.03);
}

/* Top face — catches overhead light */
.cube-face--top {
  transform: rotateX(90deg) translateZ(50px);
  background: linear-gradient(
    135deg,
    rgba(45, 45, 65, 0.9) 0%,
    rgba(35, 35, 55, 0.7) 50%,
    rgba(28, 28, 45, 0.5) 100%
  );
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: inset 0 0 12px rgba(255, 255, 255, 0.03);
}

/* Bottom face — darkest */
.cube-face--bottom {
  transform: rotateX(-90deg) translateZ(50px);
  background: rgba(15, 15, 25, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.02);
}

/* Light reflection strip on front face */
.cube-face--front::before {
  content: '';
  position: absolute;
  top: 6px;
  left: 8px;
  right: 40%;
  height: 18px;
  border-radius: 10px;
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0.08) 0%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
}

/* Volumetric shadow underneath the cube */
.cube-shadow {
  width: 80px;
  height: 14px;
  border-radius: 50%;
  background: radial-gradient(
    ellipse,
    rgba(124, 58, 237, 0.08) 0%,
    rgba(0, 0, 0, 0.04) 40%,
    transparent 70%
  );
  filter: blur(3px);
  margin-top: -6px;
  transition: all var(--duration-slow) var(--ease-spring);
}

/* Hover state for cube */
.cube-wrapper:hover .cube-shadow {
  width: 70px;
  opacity: 0.6;
  filter: blur(5px);
}

/* Icon inside cube face */
.cube-face svg {
  width: 34px;
  height: 34px;
  fill: none;
  stroke: var(--accent);
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  filter: drop-shadow(0 2px 6px rgba(124, 58, 237, 0.15));
  transition: transform var(--duration-normal) var(--ease-out);
}

.cube-wrapper:hover .cube-face svg {
  transform: scale(1.08);
}

.cube-label {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-primary);
  text-align: center;
  line-height: 1.3;
  white-space: nowrap;
  transition: color var(--duration-fast) ease;
}

.cube-wrapper:hover .cube-label {
  color: var(--accent);
}

/* ── Feature Bar (Badges) ── */
.feature-bar {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--border-radius-lg);
  padding: 1.5rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1.5rem;
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  box-shadow: var(--shadow-md);
}

.feature-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-primary);
}

.feature-icon {
  font-size: 1.15rem;
}

/* ── Stats Bar ── */
.stats-bar {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--border-radius-lg);
  padding: 2rem 3rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  box-shadow: var(--shadow-accent);
}

.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.3rem;
  text-align: center;
}

.stat-badge {
  font-size: 1.5rem;
  margin-bottom: 0.2rem;
}

.stat-val {
  font-size: 1.85rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.stat-lbl {
  font-size: 0.825rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ── Carousel ── */
.carousel-outer {
  display: flex;
  align-items: center;
  position: relative;
}

.carousel-track {
  display: flex;
  gap: 2rem;
  overflow-x: auto;
  padding: 2.5rem 1rem;
  scroll-behavior: smooth;
  scrollbar-width: none;
  width: 100%;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
}

.carousel-track::-webkit-scrollbar {
  display: none;
}

.carousel-track .cube-wrapper {
  scroll-snap-align: start;
  flex-shrink: 0;
}

.carousel-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  position: absolute;
  z-index: 15;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: all 0.25s ease;
}

.carousel-btn:hover {
  background: rgba(255, 255, 255, 0.08);
  transform: scale(1.08);
  box-shadow: var(--shadow-md);
}

.carousel-btn svg {
  width: 20px;
  height: 20px;
  fill: var(--text-primary);
}

.carousel-btn--prev { left: -22px; }
.carousel-btn--next { right: -22px; }

/* ── Search Overlay (Spotlight) ── */
.search-overlay {
  position: fixed;
  inset: 0;
  background: rgba(6, 6, 12, 0.6);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: var(--z-modal);
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding-top: 18vh;
  opacity: 0;
  visibility: hidden;
  transition: all var(--duration-normal) var(--ease-out);
}

.search-overlay.active {
  opacity: 1;
  visibility: visible;
}

.search-modal {
  width: 620px;
  max-width: 90vw;
  background: var(--glass-bg-strong);
  border: 1px solid var(--glass-border);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-xl);
  backdrop-filter: blur(30px);
  -webkit-backdrop-filter: blur(30px);
  overflow: hidden;
  transform: translateY(-20px) scale(0.97);
  transition: transform var(--duration-normal) var(--ease-spring);
}

.search-overlay.active .search-modal {
  transform: translateY(0) scale(1);
}

.search-modal-input {
  width: 100%;
  padding: 1.2rem 1.5rem;
  border: none;
  background: transparent;
  font-family: inherit;
  font-size: var(--font-size-lg);
  font-weight: 500;
  color: var(--text-primary);
  outline: none;
}

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

.search-modal-hint {
  padding: 0.8rem 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  display: flex;
  justify-content: space-between;
}

.search-modal-hint kbd {
  background: rgba(255, 255, 255, 0.06);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: inherit;
  font-size: 0.7rem;
}

/* ── Page content area (below navbar) ── */
.page-content {
  padding-top: var(--navbar-height);
}

/* ── Syllabus Page Specific ── */
.page-hero {
  padding: calc(var(--navbar-height) + var(--space-4xl)) 0 var(--space-3xl);
  text-align: center;
}

.page-hero h1 {
  font-size: var(--font-size-5xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-md);
}

.page-hero p {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  max-width: 520px;
  margin: 0 auto;
}

/* Layout: Sidebar + Cards */
.syllabus-layout {
  max-width: 1300px;
  margin: 0 auto;
  padding: 0 6%;
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: var(--space-2xl);
  min-height: 60vh;
}

/* ── Semester Sidebar ── */
.semester-sidebar {
  position: sticky;
  top: calc(var(--navbar-height) + var(--space-xl));
  height: fit-content;
}

.sidebar-label {
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: var(--space-lg);
}

.semester-tabs {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.semester-tab {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.85rem 1.2rem;
  border-radius: 14px;
  border: 1px solid transparent;
  background: transparent;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s var(--ease-out);
  text-align: left;
  width: 100%;
}

.semester-tab:hover {
  background: rgba(124, 58, 237, 0.06);
  color: var(--text-primary);
}

.semester-tab.active {
  background: var(--glass-bg-strong);
  border-color: var(--glass-border);
  color: var(--accent);
  font-weight: 600;
  box-shadow: var(--shadow-sm), 0 0 0 1px rgba(124, 58, 237, 0.06);
}

.semester-tab.active .tab-dot {
  background: var(--accent);
  box-shadow: 0 0 8px rgba(124, 58, 237, 0.3);
}

.tab-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
  flex-shrink: 0;
  transition: all 0.2s ease;
}

.tab-count {
  margin-left: auto;
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  background: var(--tab-count-bg);
  padding: 2px 8px;
  border-radius: 20px;
}

.semester-tab.active .tab-count {
  background: var(--accent-soft);
  color: var(--accent);
}

/* ── Subject Cards Grid ── */
.subjects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.subject-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--border-radius-lg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  box-shadow: var(--shadow-sm);
  padding: var(--space-xl);
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  transition: all 0.3s var(--ease-out);
  position: relative;
  overflow: hidden;
}

.subject-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--accent-gradient);
  border-radius: 3px 3px 0 0;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.subject-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(124, 58, 237, 0.12);
}

.subject-card:hover::before {
  opacity: 1;
}

.card-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.card-icon {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: var(--accent-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
}

.card-code {
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--text-muted);
  background: var(--card-code-bg);
  padding: 4px 10px;
  border-radius: 8px;
  letter-spacing: 0.04em;
}

.card-name {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.01em;
  line-height: 1.3;
}

.card-meta {
  display: flex;
  gap: var(--space-lg);
}

.card-meta-item {
  display: flex;
  flex-direction: column;
}

.card-meta-item .meta-label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.card-meta-item .meta-value {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-primary);
}

.card-units {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.unit-tag {
  font-size: 0.7rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 8px;
  background: rgba(124, 58, 237, 0.08);
  color: var(--text-secondary);
  border: 1px solid rgba(124, 58, 237, 0.12);
}

.card-actions {
  display: flex;
  gap: 0.6rem;
  margin-top: auto;
  padding-top: var(--space-sm);
}

.card-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.65rem 1rem;
  border-radius: 12px;
  font-family: inherit;
  font-size: var(--font-size-sm);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s var(--ease-out);
  border: none;
}

.card-btn--primary {
  background: var(--accent);
  color: var(--text-inverse);
  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.15);
}

.card-btn--primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(124, 58, 237, 0.25);
}

.card-btn--ghost {
  background: var(--card-code-bg);
  color: var(--text-secondary);
  border: 1px solid var(--input-border);
}

.card-btn--ghost:hover {
  background: var(--btn-secondary-hover-bg);
  color: var(--text-primary);
}

/* ── Floating Decorative Elements ── */
.floating-decor {
  position: fixed;
  pointer-events: none;
  z-index: 0;
  opacity: 0.06;
}

.floating-blueprint {
  top: 20%;
  right: -60px;
  width: 280px;
  height: 360px;
  border: 2px dashed var(--accent);
  border-radius: var(--border-radius-lg);
  transform: rotate(12deg);
  animation: floatSlow 8s ease-in-out infinite;
}

.floating-paper {
  bottom: 15%;
  left: -40px;
  width: 200px;
  height: 260px;
  background: var(--accent);
  border-radius: 8px;
  transform: rotate(-8deg);
  animation: floatSlow 10s ease-in-out infinite reverse;
}

.floating-circle {
  top: 60%;
  right: 5%;
  width: 120px;
  height: 120px;
  border: 3px solid var(--accent);
  border-radius: 50%;
  animation: floatSlow 6s ease-in-out infinite;
}

@keyframes floatSlow {
  0%, 100% { transform: translateY(0) rotate(12deg); }
  50% { transform: translateY(-20px) rotate(15deg); }
}

/* ── Empty State ── */
.empty-state {
  grid-column: 1 / -1;
  text-align: center;
  padding: var(--space-4xl) 0;
  color: var(--text-muted);
}

.empty-state .empty-icon {
  font-size: 3rem;
  margin-bottom: var(--space-md);
}

.empty-state h3 {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

/* ── Page Footer ── */
.page-footer {
  max-width: 1300px;
  margin: var(--space-5xl) auto var(--space-3xl);
  padding: 0 6%;
  text-align: center;
}

.page-footer p {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
}

.page-footer a {
  color: var(--accent);
  text-decoration: none;
}

/* ── Notes Shelf Specific ── */
.notes-shelf-container {
  display: flex;
  flex-direction: column;
  gap: var(--space-4xl);
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 6%;
}

.shelf-row {
  display: flex;
  gap: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 12px solid var(--shelf-row-border);
  border-radius: 2px;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  align-items: flex-end;
  position: relative;
}

.shelf-row::after {
  content: '';
  position: absolute;
  bottom: -12px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--shelf-row-after-bg);
}

.notebook {
  width: 54px;
  height: 240px;
  perspective: 1000px;
  cursor: pointer;
  position: relative;
  transition: transform 0.4s var(--ease-spring);
  transform-origin: bottom center;
}

.notebook:hover {
  transform: translateY(-16px) scale(1.02);
  z-index: 10;
}

.notebook-spine {
  width: 100%;
  height: 100%;
  background: linear-gradient(to right, #475569 0%, #334155 15%, #1e293b 85%, #0f172a 100%);
  border-radius: 4px 2px 2px 4px;
  box-shadow: 
    inset 2px 0 4px rgba(255,255,255,0.15),
    inset -4px 0 10px rgba(0,0,0,0.4),
    8px 0 16px rgba(0,0,0,0.1);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 1.5rem 0.4rem;
  color: #f8fafc;
  transform-style: preserve-3d;
  position: relative;
}

/* Colors for spines */
.notebook--purple .notebook-spine { background: linear-gradient(to right, #8b5cf6 0%, #7c3aed 15%, #6d28d9 85%, #4c1d95 100%); }
.notebook--blue .notebook-spine { background: linear-gradient(to right, #3b82f6 0%, #2563eb 15%, #1d4ed8 85%, #1e3a8a 100%); }
.notebook--teal .notebook-spine { background: linear-gradient(to right, #14b8a6 0%, #0d9488 15%, #0f766e 85%, #134e4a 100%); }
.notebook--rose .notebook-spine { background: linear-gradient(to right, #f43f5e 0%, #e11d48 15%, #be123c 85%, #881337 100%); }

.spine-title {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: 0.1em;
  transform: rotate(180deg);
  text-align: right;
  flex-grow: 1;
  text-shadow: 1px 1px 2px rgba(0,0,0,0.3);
  white-space: nowrap;
  font-family: var(--font-family);
  opacity: 0.9;
}

.spine-code {
  font-size: 0.65rem;
  font-weight: 700;
  text-align: center;
  margin-top: 10px;
  background: rgba(255,255,255,0.1);
  padding: 4px 2px;
  border-radius: 4px;
}

/* ── PYQs Paper Specific ── */
.pyq-container {
  max-width: 1300px;
  margin: 0 auto;
  padding: 0 6%;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(280px, 100%), 1fr));
  gap: var(--space-2xl);
}

.paper-stack {
  position: relative;
  width: 100%;
  height: 420px;
  perspective: 1500px;
  cursor: pointer;
}

.paper-sheet {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--paper-sheet-bg);
  border: 1px solid var(--paper-sheet-border);
  border-radius: 2px;
  box-shadow: 
    0 4px 12px rgba(0,0,0,0.2),
    inset 0 0 40px rgba(0,0,0,0.1);
  padding: 2rem;
  transform-origin: top left;
  transition: transform 0.6s var(--ease-spring), box-shadow 0.6s ease;
  background-image: 
    linear-gradient(var(--paper-sheet-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--paper-sheet-grid) 1px, transparent 1px);
  background-size: 20px 20px;
  color: var(--paper-sheet-text);
}

.paper-sheet--bottom {
  transform: rotate(-3deg) translate(8px, 12px);
  z-index: 1;
}

.paper-sheet--middle {
  transform: rotate(2deg) translate(4px, 6px);
  z-index: 2;
}

.paper-sheet--top {
  z-index: 3;
}

.paper-stack:hover .paper-sheet--top {
  transform: rotateX(15deg) rotateY(-10deg) translateZ(20px) translateY(-10px);
  box-shadow: 12px 20px 40px rgba(0,0,0,0.1);
}

.paper-header {
  border-bottom: 2px solid var(--paper-header-border);
  padding-bottom: 1rem;
  margin-bottom: 1rem;
  text-align: center;
}

.paper-title {
  font-family: 'Times New Roman', Times, serif;
  font-size: 1.4rem;
  font-weight: bold;
  letter-spacing: 0.02em;
  margin-bottom: 0.5rem;
}

.paper-meta {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--paper-meta-color);
  display: flex;
  justify-content: space-between;
}

.paper-body {
  font-family: monospace;
  font-size: 0.85rem;
  line-height: 1.6;
  opacity: 0.8;
}

.paper-body-line {
  height: 8px;
  background: var(--paper-body-line-bg);
  border-radius: 4px;
  margin-bottom: 12px;
}

.paper-badge {
  position: absolute;
  top: 1rem;
  right: -0.5rem;
  background: var(--accent);
  color: white;
  padding: 4px 12px;
  font-size: 0.7rem;
  font-weight: 700;
  box-shadow: 0 4px 10px rgba(124, 58, 237, 0.3);
  border-radius: 4px;
}

/* ── Responsive: Tablet ── */
@media (max-width: 900px) {
  .syllabus-layout {
    grid-template-columns: 1fr;
  }

  .semester-sidebar {
    position: static;
  }

  .semester-tabs {
    flex-direction: row;
    overflow-x: auto;
    scrollbar-width: none;
    gap: 8px;
    padding-bottom: 4px;
  }

  .semester-tabs::-webkit-scrollbar { display: none; }

  .semester-tab {
    white-space: nowrap;
    padding: 0.7rem 1rem;
  }

  .page-hero h1 {
    font-size: var(--font-size-3xl);
  }

  .section-header h2 {
    font-size: var(--font-size-3xl);
  }
}

/* Mobile menu overlay default state (hidden on desktop) */
.mobile-menu-overlay {
  display: none;
}

/* ── Mobile & Tablet Responsiveness ── */
@media (max-width: 768px) {
  /* Layout Spacing */
  :root {
    --space-4xl: 3.5rem;
    --space-5xl: 5rem;
  }

  .section-container {
    padding: 0 1.25rem;
  }

  /* Typography scale down */
  .hero-title {
    font-size: 2rem !important;
    line-height: 1.18 !important;
  }

  .hero-desc {
    font-size: 0.975rem !important;
  }

  /* Hero action buttons — stack vertically on mobile */
  .hero-actions {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
    max-width: 300px;
  }

  /* Section headers */
  .section-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
    margin-bottom: var(--space-xl);
  }

  .section-header h2 {
    font-size: var(--font-size-2xl);
  }

  /* Navbar Mobile Layout */
  .navbar {
    padding: 0 1.25rem;
  }

  .nav-center,
  .nav-right .search-wrapper,
  .nav-right .btn-signin,
  .nav-right .theme-toggle {
    display: none !important;
  }

  .mobile-nav-toggle {
    display: flex;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-primary);
    width: 44px;
    height: 44px;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
    transition: background 0.2s ease;
  }

  .mobile-nav-toggle:active {
    background: rgba(255, 255, 255, 0.06);
  }

  /* Mobile menu fullscreen overlay */
  .mobile-menu-overlay {
    position: fixed;
    inset: 0;
    background: var(--bg-primary);
    z-index: 98;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2.5rem;
    opacity: 0;
    visibility: hidden;
    transition: all 0.35s var(--ease-out);
  }

  .mobile-menu-overlay.active {
    opacity: 1;
    visibility: visible;
  }

  .mobile-menu-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
  }

  .mobile-menu-links a {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    transition: color 0.2s;
  }

  .mobile-menu-links a:hover,
  .mobile-menu-links a.active {
    color: var(--accent);
  }

  /* Feature bar — 2-column grid on mobile */
  .feature-bar {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    padding: 1.25rem 1.25rem;
  }

  .feature-item {
    font-size: 0.875rem;
  }

  /* Stats bar — 2-column grid on mobile */
  .stats-bar {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    padding: 1.75rem 1.5rem;
  }

  .stat-item {
    width: 100%;
    border-bottom: none;
    padding-bottom: 0;
  }

  /* Carousel swipe improvements */
  .carousel-btn {
    display: none !important;
  }

  .carousel-track {
    gap: 1.25rem;
    padding: 1.5rem 0.75rem;
  }

  /* Notebook shelf — horizontal scroll on mobile */
  .notes-shelf-container {
    padding: 0 1.25rem;
    gap: var(--space-3xl);
  }

  .shelf-row {
    overflow-x: auto;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
    scroll-snap-type: x mandatory;
    flex-wrap: nowrap;
    gap: 0.75rem;
    padding-bottom: 0.5rem;
  }

  .shelf-row::-webkit-scrollbar { display: none; }

  .notebook {
    scroll-snap-align: start;
    flex-shrink: 0;
    height: 180px;
    width: 44px;
  }

  /* PYQ paper stack — reduced height on mobile */
  .paper-stack {
    height: 320px;
  }

  /* Syllabus layout */
  .syllabus-layout {
    grid-template-columns: 1fr;
  }
}

/* ── Micro Breakpoint: Very Small Phones (≤ 480px) ── */
@media (max-width: 480px) {
  .hero-title {
    font-size: 1.75rem !important;
  }

  .hero-badge {
    font-size: 0.65rem;
  }

  .section-header h2 {
    font-size: var(--font-size-xl);
  }

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

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

  .pyq-container {
    padding: 0 1.25rem;
    gap: var(--space-xl);
  }

  .paper-stack {
    height: 290px;
  }

  .paper-title {
    font-size: 1.1rem;
  }

  .paper-body {
    font-size: 0.78rem;
  }

  .notes-shelf-container {
    padding: 0 1rem;
  }

  .notebook {
    height: 160px;
    width: 40px;
  }

  .page-hero h1,
  .notes-hero h1,
  .pyqs-hero h1,
  .founder-hero h1,
  .roadmap-hero h1,
  .ai-header h1 {
    font-size: var(--font-size-2xl);
  }

  .page-hero p,
  .notes-hero p,
  .pyqs-hero p,
  .founder-hero p,
  .roadmap-hero p {
    font-size: var(--font-size-sm);
  }
}

/* ── Reduced Motion ── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .wheel {
    animation: none;
  }

  canvas {
    transition: none !important;
  }
}

/* ── Syllabus Dashboard Section (Home Integrated) ── */
.syllabus-section-wrapper {
  margin-top: var(--space-4xl);
}

.syllabus-layout-dashboard {
  display: flex;
  gap: 3rem;
  width: 100%;
}

@media (max-width: 1024px) {
  .syllabus-layout-dashboard {
    flex-direction: column;
    gap: 2rem;
  }
  .preview-column {
    width: 100% !important;
  }
  .showcase-scene-container {
    display: none !important;
  }
}

.explorer-column {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2.2rem;
}

.explorer-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 2rem;
}

@media (max-width: 600px) {
  .explorer-header {
    flex-direction: column;
    align-items: stretch;
    gap: 1rem;
  }
}

.header-titles h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.header-titles p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  font-weight: 400;
}

.update-alert-card {
  background: var(--bg-secondary);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--border-radius-md);
  padding: 0.85rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  box-shadow: var(--shadow-sm);
  flex-shrink: 0;
}

.update-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
}

.update-info {
  display: flex;
  flex-direction: column;
}

.update-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.update-value {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* Semester Tabs Pill Bar */
.semester-tabs-container {
  background: var(--bg-secondary);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 30px;
  padding: 6px;
  display: flex;
  overflow-x: auto;
  scrollbar-width: none;
  box-shadow: var(--shadow-sm);
  width: 100%;
  max-width: 100%;
}

.semester-tabs-container::-webkit-scrollbar {
  display: none;
}

.sem-pill-btn {
  flex-shrink: 0;
  background: none;
  border: none;
  padding: 0.7rem 1.2rem;
  border-radius: 25px;
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.25s var(--ease-out);
}

.sem-pill-btn:hover {
  color: var(--text-primary);
}

.sem-pill-btn.active {
  background: var(--accent);
  color: #ffffff;
  box-shadow: 0 4px 15px rgba(124, 58, 237, 0.25);
}

/* Active Sem Header Banner */
.active-sem-banner {
  display: flex;
  align-items: center;
  gap: 1.2rem;
}

.sem-banner-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: var(--accent-soft);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
}

.sem-banner-info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.sem-title-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.sem-title-row h2 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.subjects-count-badge {
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 20px;
}

.sem-banner-info p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Subject Accordions */
.subject-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.subject-row {
  background: var(--bg-secondary);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--border-radius-md);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: border-color 0.2s;
}

.subject-row:hover {
  border-color: rgba(124, 58, 237, 0.15);
}

.subject-summary {
  display: flex;
  align-items: center;
  padding: 1.2rem 1.5rem;
  cursor: pointer;
  user-select: none;
  gap: 1.2rem;
}

.subject-row-icon {
  width: 42px;
  height: 42px;
  border-radius: 10px;
  background: var(--bg-primary);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
}

.subject-row-info {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.subject-row-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
}

.subject-row-desc {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.subject-row-meta {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.subject-code-badge {
  background: var(--bg-primary);
  color: var(--text-secondary);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 8px;
}

.chevron-icon {
  color: var(--text-muted);
  font-size: 1rem;
  transition: transform 0.3s;
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.subject-row.open .chevron-icon {
  transform: rotate(180deg);
}

/* Accordion Expanded Details Content */
.subject-details {
  display: none;
  padding: 0 1.5rem 1.5rem 4.5rem;
  border-top: 1px dashed rgba(255, 255, 255, 0.06);
  background: var(--bg-warm);
}

.subject-row.open .subject-details {
  display: block;
  animation: slideDown 0.3s var(--ease-out);
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

.syllabus-units {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
  margin-top: 1.2rem;
}

@media (max-width: 600px) {
  .syllabus-units {
    grid-template-columns: 1fr;
  }
  .subject-details {
    padding: 0 1rem 1.25rem 1rem;
  }
}

.unit-box {
  background: var(--bg-secondary);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 10px;
  padding: 1rem;
}

.unit-title {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.4rem;
}

.unit-topics {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.unit-actions-row {
  display: flex;
  gap: 1rem;
  margin-top: 1.2rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.action-link {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: color 0.2s;
}

.action-link:hover {
  color: var(--accent-hover);
}

/* Right Side Column */
.preview-column {
  width: 440px;
  display: flex;
  flex-direction: column;
  gap: 2.2rem;
}

/* Download Card (Bottom right) */
.download-section-card {
  background: var(--bg-secondary);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--border-radius-lg);
  padding: 1.25rem;
  display: flex;
  align-items: center;
  gap: 1.25rem;
  text-decoration: none;
  color: inherit;
  box-shadow: var(--shadow-sm);
  transition: all 0.3s var(--ease-out);
  position: relative;
  overflow: hidden;
}

.download-section-card:hover {
  transform: translateY(-4px);
  border-color: rgba(124, 58, 237, 0.15);
  box-shadow: var(--shadow-md), 0 12px 20px rgba(124, 58, 237, 0.04);
}

.download-btn-circle {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s;
}

.download-section-card:hover .download-btn-circle {
  background: var(--accent);
  color: #ffffff;
  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.2);
}

.download-card-info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  flex: 1;
}

.download-card-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
}

.download-card-sub {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.download-card-icon {
  color: var(--text-muted);
  transition: transform 0.3s var(--ease-out);
}

.download-section-card:hover .download-card-icon {
  transform: translateX(4px);
  color: var(--accent);
}

/* ── Notes and PYQs Filters ── */
.notes-filter-bar, .pyqs-filter-bar {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.filter-btn {
  padding: 0.6rem 1.2rem;
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  font-family: inherit;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.filter-btn:hover {
  background: rgba(124, 58, 237, 0.04);
  color: var(--text-primary);
}

.filter-btn.active {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
  box-shadow: 0 4px 12px rgba(124, 58, 237, 0.2);
}

.filter-select {
  padding: 0.6rem 1.2rem;
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  font-family: inherit;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  outline: none;
  -webkit-appearance: none;
  appearance: none;
}

.filter-select:hover {
  border-color: rgba(124, 58, 237, 0.3);
}

/* Mobile responsive filters */
@media (max-width: 768px) {
  .notes-filter-bar {
    justify-content: flex-start;
    gap: 0.5rem;
    overflow-x: auto;
    flex-wrap: nowrap;
    scrollbar-width: none;
  }
  .notes-filter-bar::-webkit-scrollbar { display: none; }
  .filter-btn {
    white-space: nowrap;
    flex-shrink: 0;
  }

  .pyqs-filter-bar {
    flex-direction: column;
    align-items: stretch;
    gap: 0.75rem;
  }
  .filter-select {
    width: 100%;
    padding: 0.75rem 1rem;
    border-radius: 12px;
    font-size: 1rem;
  }

}

/* ── Branch Selection Section ── */
.branch-selection-section {
  padding: var(--space-3xl) 6% var(--space-4xl);
  max-width: 1400px;
  margin: 0 auto;
}

.path-finder-container {
  display: grid;
  grid-template-columns: 55% 45%;
  gap: 2rem;
  margin-top: 2.5rem;
}

.finder-panel {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-2xl);
  padding: 2.2rem 2rem;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
}

.panel-label {
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  display: block;
}

/* Branches Grid */
.branches-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
}

.branch-pill {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.9rem 1.25rem;
  border-radius: var(--border-radius-xl);
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: var(--font-size-sm);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  text-align: left;
}

.branch-pill-icon {
  font-size: 1.25rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.branch-pill:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
  transform: translateY(-2px);
}

.branch-pill.active {
  background: var(--accent-soft);
  border-color: rgba(124, 58, 237, 0.3);
  color: var(--accent);
  box-shadow: 0 4px 20px rgba(124, 58, 237, 0.1);
}

/* Semesters Grid */
.semesters-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.85rem;
}

.sem-card-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.25rem 0.5rem;
  border-radius: var(--border-radius-xl);
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  font-family: inherit;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  gap: 0.35rem;
}

.sem-num {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  transition: color 0.3s ease;
}

.sem-text {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.sem-card-btn:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(255, 255, 255, 0.1);
  transform: translateY(-2px);
}

.sem-card-btn:hover .sem-num {
  color: var(--accent);
}

.sem-card-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  box-shadow: 0 8px 25px rgba(124, 58, 237, 0.3);
}

.sem-card-btn.active .sem-num,
.sem-card-btn.active .sem-text {
  color: #ffffff;
}

/* Responsive Path Finder */
@media (max-width: 1024px) {
  .path-finder-container {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
}

@media (max-width: 480px) {
  .branches-grid {
    grid-template-columns: 1fr;
  }
  .semesters-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}