/**
 * DevFluentia — Premium Light Academic Design System
 * Visual Identity: Prestigious University Publication & Contemporary Educational Platform.
 * Palette: Pure White, Warm White, Ivory, Academic Navy, Refined Blue & Muted Gold.
 */

:root {
  /* Exact Specified Palette */
  --bg-pure-white: #FFFFFF;
  --bg-warm-white: #FAF9F6;
  --bg-ivory: #F2EFE7;
  --bg-surface-blue: #EEF4F9;
  
  --text-primary: #202A36;
  --text-secondary: #687586;
  --text-muted: #8896A6;
  --text-inverse: #FFFFFF;

  --academic-navy: #233D5B;
  --academic-navy-dark: #172B42;
  --academic-navy-light: #2D4C70;

  --refined-blue: #547CA5;
  --refined-blue-light: #6E95BE;
  --refined-blue-dim: rgba(84, 124, 165, 0.09);
  --refined-blue-border: rgba(84, 124, 165, 0.25);

  --academic-gold: #B69A63;
  --academic-gold-dark: #967D4B;
  --academic-gold-light: #CCA866;
  --academic-gold-dim: rgba(182, 154, 99, 0.1);
  --academic-gold-border: rgba(182, 154, 99, 0.3);

  --border-subtle: #E5E7EB;
  --border-card: #E5E7EB;
  --border-card-hover: #D1D5DB;

  /* Typography Families */
  --font-serif: 'Playfair Display', Georgia, 'Times New Roman', serif;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-ui: 'Manrope', 'Inter', sans-serif;
  --font-display: 'Playfair Display', Georgia, serif;

  /* Dimensions & Radii */
  --header-height: 74px;
  --container-max: 1220px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 26px;
  --radius-full: 9999px;

  /* Natural Soft Academic Shadows */
  --shadow-xs: 0 1px 3px rgba(32, 42, 54, 0.04);
  --shadow-sm: 0 2px 8px rgba(32, 42, 54, 0.04), 0 1px 2px rgba(32, 42, 54, 0.02);
  --shadow-md: 0 8px 24px rgba(32, 42, 54, 0.06), 0 2px 6px rgba(32, 42, 54, 0.03);
  --shadow-lg: 0 16px 40px rgba(32, 42, 54, 0.08), 0 4px 12px rgba(32, 42, 54, 0.04);
  --shadow-card-hover: 0 14px 34px rgba(35, 61, 91, 0.09), 0 4px 10px rgba(35, 61, 91, 0.04);
  --shadow-navy-btn: 0 4px 16px rgba(35, 61, 91, 0.2);
  --shadow-gold-btn: 0 4px 16px rgba(182, 154, 99, 0.22);

  /* Transitions */
  --transition-fast: 0.18s ease;
  --transition-normal: 0.24s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-smooth: 0.38s cubic-bezier(0.16, 1, 0.3, 1);

  /* ══════════════════════════════════════════════
     FOUR WORLDS DESIGN SYSTEM
     Space × Nature × Ocean × Geometry
     ══════════════════════════════════════════════ */

  /* OCEAN — Ch3, Section 3.1 */
  --ocean-deep: #0A1628;
  --ocean-midnight: #0D1F3C;
  --ocean-abyss: #071220;
  --ocean-blue: #1A4B6E;
  --ocean-teal: #1B6B7A;
  --ocean-cyan: #2A9BB5;
  --ocean-light: #4DC4DD;
  --ocean-foam: #A8E6F0;
  --ocean-glow: rgba(45, 155, 181, 0.35);
  --ocean-dim: rgba(26, 75, 110, 0.18);
  --ocean-border: rgba(77, 196, 221, 0.28);

  /* NATURE (Botanical) — Ch3, Section 3.2 */
  --nature-deep: #1A2E1A;
  --nature-forest: #1E3D1E;
  --nature-botanical: #2D5A27;
  --nature-sage: #4A7C5A;
  --nature-leaf: #5E9E62;
  --nature-mint: #8BC89A;
  --nature-ivory: #F2EFDE;
  --nature-cream: #FAF7ED;
  --nature-gold: #C4A44A;
  --nature-glow: rgba(46, 90, 39, 0.3);
  --nature-dim: rgba(46, 90, 39, 0.12);
  --nature-border: rgba(94, 158, 98, 0.3);

  /* SPACE — Ch4, Section 4.1 */
  --space-void: #050A14;
  --space-midnight: #080E1E;
  --space-nebula: #0E1A3A;
  --space-indigo: #1E2D5E;
  --space-violet: #2D2060;
  --space-aurora: #3D1A6E;
  --space-stardust: #8B9ECC;
  --space-silver: #C4CCDD;
  --space-gold: #D4AF60;
  --space-glow: rgba(50, 80, 160, 0.3);
  --space-dim: rgba(30, 45, 94, 0.2);
  --space-border: rgba(139, 158, 204, 0.28);

  /* GEOMETRY — Ch4, Section 4.2 */
  --geo-white: #FAFBFC;
  --geo-off-white: #F5F6F8;
  --geo-light: #EEF0F4;
  --geo-line: #DDE1E8;
  --geo-slate: #8694A8;
  --geo-navy: #1E2D42;
  --geo-accent: #3F5B84;
  --geo-gold: #C09F58;
  --geo-glow: rgba(63, 91, 132, 0.12);
  --geo-dim: rgba(30, 45, 66, 0.06);
  --geo-border: rgba(63, 91, 132, 0.22);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-pure-white);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.65;
  overflow-x: hidden;
  position: relative;
}

/* Academic Architectural Background Layers */
.bg-ambient-layer {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background: 
    radial-gradient(ellipse 900px 600px at 5% 5%, rgba(242, 239, 231, 0.75), transparent 70%),
    radial-gradient(ellipse 800px 500px at 95% 95%, rgba(238, 244, 249, 0.8), transparent 75%),
    #FFFFFF;
}

.bg-academic-canvas {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 1;
  background-image: 
    linear-gradient(to right, rgba(32, 42, 54, 0.018) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(32, 42, 54, 0.018) 1px, transparent 1px);
  background-size: 64px 64px;
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 9px;
  height: 9px;
}

::-webkit-scrollbar-track {
  background: var(--bg-warm-white);
}

::-webkit-scrollbar-thumb {
  background: #CBD5E1;
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--academic-navy);
}

/* Keyboard Accessibility */
:focus-visible {
  outline: 2px solid var(--academic-navy);
  outline-offset: 3px;
  border-radius: 4px;
}

/* Typography Hierarchy */
h1, h2, h3, h4, h5, h6 {
  color: var(--academic-navy);
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.25;
}

p {
  color: var(--text-secondary);
}

a {
  color: inherit;
  text-decoration: none;
}

.section-label {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--academic-navy);
}

.section-label.gold {
  color: var(--academic-gold-dark);
}

.section-label.blue {
  color: var(--refined-blue);
}

/* Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 28px;
  padding-right: 28px;
  position: relative;
  z-index: 3;
}

/* ===================================================
   GLOBAL NAVIGATION BAR
   =================================================== */
.main-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-subtle);
  z-index: 100;
  display: flex;
  align-items: center;
  box-shadow: 0 2px 10px rgba(32, 42, 54, 0.03);
  transition: transform 0.35s cubic-bezier(0.22, 1, 0.36, 1), background var(--transition-fast), box-shadow 0.35s ease;
  will-change: transform;
}

.main-header.header-hidden {
  transform: translateY(-100%);
  box-shadow: none;
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  transition: opacity var(--transition-fast);
}

.brand-link:hover {
  opacity: 0.88;
}

.brand-logo-img {
  height: 42px;
  width: auto;
  max-width: 140px;
  object-fit: contain;
  display: block;
}

.brand-title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--academic-navy);
}

.brand-subtitle-badge {
  font-family: var(--font-ui);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--academic-gold-dark);
  background: var(--bg-warm-white);
  border: 1px solid var(--academic-gold-border);
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  margin-left: 6px;
}

.nav-menu-desktop {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-item-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-family: var(--font-ui);
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  background: transparent;
  border: 1px solid transparent;
}

.nav-item-btn:hover {
  color: var(--academic-navy);
  background: var(--bg-warm-white);
}

.nav-item-btn.active {
  color: var(--academic-navy);
  background: var(--bg-surface-blue);
  border-color: var(--border-subtle);
  font-weight: 700;
}

.nav-item-btn.active-ch3 {
  color: var(--refined-blue);
  border-color: var(--refined-blue-border);
  background: var(--refined-blue-dim);
}

.nav-item-btn.active-ch4 {
  color: var(--academic-gold-dark);
  border-color: var(--academic-gold-border);
  background: var(--academic-gold-dim);
}

.mobile-menu-toggle {
  display: none;
  background: var(--bg-warm-white);
  border: 1px solid var(--border-subtle);
  color: var(--academic-navy);
  padding: 8px;
  border-radius: var(--radius-md);
  cursor: pointer;
  align-items: center;
  justify-content: center;
}

.mobile-nav-drawer {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 24px 28px;
  z-index: 99;
  flex-direction: column;
  gap: 10px;
  box-shadow: var(--shadow-lg);
}

.mobile-nav-drawer.open {
  display: flex;
}

/* Reusable Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  font-family: var(--font-ui);
  font-size: 0.92rem;
  font-weight: 700;
  padding: 13px 26px;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-normal);
  border: 1px solid transparent;
  text-decoration: none;
}

.btn-primary {
  background: var(--academic-navy);
  color: var(--text-inverse);
  box-shadow: var(--shadow-navy-btn);
}

.btn-primary:hover {
  background: var(--academic-navy-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 22px rgba(35, 61, 91, 0.28);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-gold {
  background: var(--academic-gold);
  color: var(--text-inverse);
  box-shadow: var(--shadow-gold-btn);
}

.btn-gold:hover {
  background: var(--academic-gold-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 22px rgba(182, 154, 99, 0.3);
}

.btn-blue {
  background: var(--refined-blue);
  color: var(--text-inverse);
  box-shadow: 0 4px 16px rgba(84, 124, 165, 0.22);
}

.btn-blue:hover {
  background: var(--refined-blue-light);
  transform: translateY(-2px);
}

.btn-secondary {
  background: var(--bg-pure-white);
  color: var(--academic-navy);
  border: 1px solid var(--border-card);
  box-shadow: var(--shadow-xs);
}

.btn-secondary:hover {
  background: var(--bg-warm-white);
  border-color: var(--border-card-hover);
  color: var(--academic-navy-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

/* ===================================================
   01. OPENING SCREEN (Team Presentation Cover)
   =================================================== */
.opening-view {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 48px 24px;
  position: relative;
  z-index: 3;
  text-align: center;
  background: linear-gradient(180deg, #FFFFFF 0%, var(--bg-warm-white) 100%);
}

/* Subtle Floating Academic Book Ornaments (Pointer-events: None) */
.academic-floating-decorations {
  position: absolute;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
  z-index: 1;
}

.floating-book-item {
  position: absolute;
  color: var(--refined-blue);
  opacity: 0.16;
  filter: drop-shadow(0 4px 10px rgba(32, 42, 54, 0.04));
  animation: floatBook linear infinite;
  pointer-events: none;
}

.floating-book-1 {
  top: 10%;
  left: 6%;
  width: 50px;
  height: 50px;
  animation-duration: 6.8s;
}

.floating-book-2 {
  top: 16%;
  right: 8%;
  width: 46px;
  height: 46px;
  color: var(--academic-gold);
  opacity: 0.22;
  animation-duration: 7.4s;
  animation-delay: -2s;
}

.floating-book-3 {
  bottom: 12%;
  left: 8%;
  width: 42px;
  height: 42px;
  color: var(--academic-gold);
  opacity: 0.2;
  animation-duration: 6.2s;
  animation-delay: -1.5s;
}

.floating-book-4 {
  bottom: 16%;
  right: 7%;
  width: 54px;
  height: 54px;
  animation-duration: 8s;
  animation-delay: -3.5s;
}

@keyframes floatBook {
  0% { transform: translateY(0px) rotate(0deg); }
  50% { transform: translateY(-7px) rotate(1.5deg); }
  100% { transform: translateY(0px) rotate(0deg); }
}

.opening-logo-wrapper {
  margin-bottom: 22px;
  position: relative;
  z-index: 2;
}

.opening-logo-img {
  max-height: 82px;
  max-width: 240px;
  object-fit: contain;
  filter: drop-shadow(0 4px 14px rgba(32, 42, 54, 0.06));
}

.opening-title {
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 5.5vw, 4.2rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--academic-navy);
  margin-bottom: 6px;
  line-height: 1.15;
}

.opening-subtitle {
  font-family: var(--font-ui);
  font-size: clamp(0.95rem, 2vw, 1.25rem);
  font-weight: 700;
  color: var(--academic-gold-dark);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  margin-bottom: 14px;
}

.opening-tagline {
  font-size: clamp(1rem, 1.8vw, 1.18rem);
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 38px;
  line-height: 1.7;
}

/* Team Grid on Opening Screen: Equal Presentation, NO Roles/Labels */
.team-section-heading {
  font-family: var(--font-ui);
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.team-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  width: 100%;
  max-width: 980px;
  margin-bottom: 46px;
  position: relative;
  z-index: 2;
}

/* Equal Floating Profile Cards (Display Only Image & Name) */
.team-card {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 28px 18px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal), border-color var(--transition-normal);
  position: relative;
  min-height: 200px;
}

/* Restrained Floating Movements (5-8px over 5.2s - 6.8s cycles) */
.team-card-float-0 {
  animation: floatProfile 5.4s ease-in-out infinite;
}

.team-card-float-1 {
  animation: floatProfile 6.4s ease-in-out infinite;
  animation-delay: -1.6s;
}

.team-card-float-2 {
  animation: floatProfile 5.8s ease-in-out infinite;
  animation-delay: -3.2s;
}

.team-card-float-3 {
  animation: floatProfile 6.9s ease-in-out infinite;
  animation-delay: -0.8s;
}

@keyframes floatProfile {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-6px); }
  100% { transform: translateY(0px); }
}

.team-card:hover {
  transform: translateY(-8px) !important;
  border-color: var(--refined-blue-border);
  box-shadow: var(--shadow-card-hover);
  background: #FFFFFF;
}

.portrait-wrapper {
  position: relative;
  width: 100px;
  height: 100px;
  margin-bottom: 16px;
  flex-shrink: 0;
}

.portrait-img {
  width: 100%;
  height: 100%;
  border-radius: var(--radius-full);
  object-fit: cover;
  object-position: center top;
  display: block;
  border: 2px solid rgba(35, 61, 91, 0.12);
  box-shadow: 0 4px 14px rgba(32, 42, 54, 0.08);
  background-color: var(--bg-warm-white);
}

.portrait-placeholder {
  width: 100%;
  height: 100%;
  border-radius: var(--radius-full);
  background: var(--bg-warm-white);
  border: 1.5px dashed var(--refined-blue-border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--refined-blue);
  box-shadow: 0 4px 12px rgba(32, 42, 54, 0.04);
}

.team-card-name {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--academic-navy);
  text-align: center;
  line-height: 1.3;
}

/* ===================================================
   02. MAIN LESSON OVERVIEW (Editorial Layout)
   =================================================== */
.overview-hero-wrapper {
  padding: 110px 0 48px;
  position: relative;
}

/* Grand Panoramic Editorial Hero with Sunlit Campus Background */
.overview-grand-hero {
  position: relative;
  min-height: 500px;
  border-radius: var(--radius-2xl);
  border: 1px solid var(--border-card);
  box-shadow: 0 20px 48px -12px rgba(35, 61, 91, 0.14), 0 4px 16px rgba(32, 42, 54, 0.04);
  overflow: hidden;
  margin-bottom: 52px;
  display: flex;
  align-items: center;
  background-color: var(--bg-pure-white);
}

.grand-hero-bg-layer {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  user-select: none;
  z-index: 1;
}

.grand-hero-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 32%;
  display: block;
  transform: scale(1.02);
  filter: saturate(1.08) brightness(1.02);
}

.grand-hero-scrim {
  position: absolute;
  inset: 0;
  /* World-class multi-stop academic gradient: pristine white/ivory wash on the left protecting the text, fading gently to reveal the sunlit campus on the right */
  background: 
    linear-gradient(90deg, 
      rgba(255, 255, 255, 0.98) 0%, 
      rgba(255, 255, 255, 0.95) 34%, 
      rgba(255, 255, 255, 0.84) 56%, 
      rgba(255, 255, 255, 0.48) 80%, 
      rgba(255, 255, 255, 0.18) 100%
    ),
    linear-gradient(180deg, 
      rgba(255, 255, 255, 0.3) 0%, 
      transparent 50%, 
      rgba(250, 249, 246, 0.85) 100%
    );
}

.grand-hero-content {
  position: relative;
  z-index: 2;
  max-width: 680px;
  padding: 56px 52px;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-ui);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--academic-navy);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--border-card);
  padding: 7px 16px;
  border-radius: var(--radius-full);
  margin-bottom: 20px;
  box-shadow: 0 2px 8px rgba(35, 61, 91, 0.05);
}

.hero-heading {
  font-family: var(--font-serif);
  font-size: clamp(2.3rem, 4.2vw, 3.4rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  color: var(--academic-navy);
  margin-bottom: 18px;
  line-height: 1.18;
}

.hero-description {
  font-size: 1.14rem;
  color: #4b5868;
  line-height: 1.72;
  margin-bottom: 28px;
  font-weight: 450;
}

.hero-actions-row {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-bottom: 30px;
}

.grand-hero-highlights {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.highlight-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(229, 231, 235, 0.88);
  box-shadow: 0 2px 8px rgba(35, 61, 91, 0.04);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  line-height: 1.4;
  color: var(--academic-navy);
}

.highlight-chip-dot {
  width: 7px;
  height: 7px;
  border-radius: var(--radius-full);
  flex-shrink: 0;
}
.highlight-chip-dot.blue { background: var(--refined-blue); }
.highlight-chip-dot.gold { background: var(--academic-gold); }
.highlight-chip-dot.navy { background: var(--academic-navy); }

.highlight-chip-title {
  font-weight: 700;
  font-family: var(--font-ui);
  letter-spacing: 0.02em;
}

.highlight-chip-text {
  color: var(--text-secondary);
}

/* Prominent Lesson Summary Carousel Component */
.prominent-summary-section {
  margin-bottom: 50px;
}

.carousel-container {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-xl);
  padding: 42px 48px;
  position: relative;
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.carousel-top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 22px;
}

.carousel-heading-wrap {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.carousel-main-title {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--academic-navy);
}

.carousel-badge {
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 4px 12px;
  border-radius: var(--radius-sm);
  background: var(--bg-warm-white);
  color: var(--academic-gold-dark);
  border: 1px solid var(--academic-gold-border);
}

.carousel-progress-track {
  width: 100%;
  height: 3px;
  background: var(--border-subtle);
  border-radius: var(--radius-full);
  margin-bottom: 26px;
  overflow: hidden;
}

.carousel-progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--academic-navy), var(--academic-gold));
  border-radius: var(--radius-full);
}

/* Fixed/Min-Height Viewport to Completely Prevent Layout Shifts */
.carousel-slide-viewport {
  min-height: 135px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  transition: opacity var(--transition-fast);
}

.carousel-slide-headline {
  font-family: var(--font-serif);
  font-size: clamp(1.4rem, 2.5vw, 1.85rem);
  font-weight: 700;
  color: var(--academic-navy);
  margin-bottom: 10px;
  line-height: 1.3;
}

.carousel-slide-text {
  font-size: 1.08rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.carousel-controls-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 28px;
  padding-top: 22px;
  border-top: 1px solid var(--border-subtle);
}

.carousel-indicators {
  display: flex;
  gap: 8px;
}

.carousel-dot {
  width: 24px;
  height: 4px;
  background: #CBD5E1;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
}

.carousel-dot.active {
  width: 42px;
  background: var(--academic-navy);
}

.carousel-nav-buttons {
  display: flex;
  align-items: center;
  gap: 10px;
}

.carousel-btn {
  background: var(--bg-warm-white);
  border: 1px solid var(--border-card);
  color: var(--academic-navy);
  width: 38px;
  height: 38px;
  border-radius: var(--radius-md);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.carousel-btn:hover {
  color: var(--text-inverse);
  background: var(--academic-navy);
  border-color: var(--academic-navy);
  transform: translateY(-1px);
}

/* Chapter Cards Section */
.overview-chapters-section {
  padding-bottom: 80px;
}

.chapters-cards-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.chapter-big-card {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-xl);
  padding: 38px;
  position: relative;
  overflow: hidden;
  transition: all var(--transition-normal);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
}

.chapter-big-card.ch3-theme {
  border-top: 4px solid var(--refined-blue);
}

.chapter-big-card.ch4-theme {
  border-top: 4px solid var(--academic-gold);
}

.chapter-big-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-card-hover);
  border-color: var(--border-card-hover);
}

.chapter-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 18px;
}

.chapter-num-badge {
  font-family: var(--font-ui);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  padding: 5px 14px;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
}

.ch3-theme .chapter-num-badge {
  color: var(--refined-blue);
  background: var(--refined-blue-dim);
  border: 1px solid var(--refined-blue-border);
}

.ch4-theme .chapter-num-badge {
  color: var(--academic-gold-dark);
  background: var(--academic-gold-dim);
  border: 1px solid var(--academic-gold-border);
}

.chapter-card-icon-bubble {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border-subtle);
  background: var(--bg-warm-white);
}

.ch3-theme .chapter-card-icon-bubble {
  color: var(--refined-blue);
}

.ch4-theme .chapter-card-icon-bubble {
  color: var(--academic-gold-dark);
}

.chapter-card-title {
  font-family: var(--font-serif);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--academic-navy);
  margin-bottom: 12px;
  line-height: 1.25;
}

.chapter-card-desc {
  font-size: 0.98rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 28px;
}

.chapter-sections-preview-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 30px;
  padding: 18px;
  border-radius: var(--radius-md);
  background: var(--bg-warm-white);
  border: 1px solid var(--border-subtle);
}

.section-preview-item {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.88rem;
  color: var(--text-primary);
  font-weight: 500;
}

.section-preview-num {
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  background: #FFFFFF;
  border: 1px solid var(--border-subtle);
  color: var(--academic-navy);
}

/* ===================================================
   03. CHAPTER LANDING PAGES
   =================================================== */
.page-top-spacer {
  padding-top: calc(var(--header-height) + 32px);
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-ui);
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.breadcrumb-item {
  color: var(--text-muted);
  cursor: pointer;
  transition: color var(--transition-fast);
}

.breadcrumb-item:hover {
  color: var(--academic-navy);
}

.breadcrumb-item.active {
  color: var(--academic-navy);
  font-weight: 700;
}

.breadcrumb-separator {
  color: #CBD5E1;
}

/* Chapter Hero Banners */
.chapter-hero-banner {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-xl);
  padding: 44px;
  margin-bottom: 40px;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.chapter-hero-banner.ch3-style {
  border-left: 5px solid var(--refined-blue);
  background: linear-gradient(135deg, #FFFFFF 0%, rgba(84, 124, 165, 0.05) 100%);
}

.chapter-hero-banner.ch4-style {
  border-left: 5px solid var(--academic-gold);
  background: linear-gradient(135deg, #FFFFFF 0%, rgba(182, 154, 99, 0.05) 100%);
}

.three-sections-cards-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 48px;
}

.section-entry-card {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition-normal);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
}

.section-entry-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-card-hover);
  box-shadow: var(--shadow-card-hover);
}

.section-card-num-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.section-pill {
  font-family: var(--font-ui);
  font-size: 0.74rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: var(--bg-warm-white);
  color: var(--academic-navy);
}

/* ===================================================
   04. TEACHING PAGES DEDICATED STRUCTURE
   =================================================== */
.teaching-content-wrapper {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 40px;
  margin-bottom: 60px;
}

.teaching-main-column {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.teaching-sidebar-column {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

/* Academic Structured Content Box */
.card-academic {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: all var(--transition-normal);
  position: relative;
  box-shadow: var(--shadow-sm);
}

.card-academic:hover {
  border-color: var(--border-card-hover);
  box-shadow: var(--shadow-md);
}

/* Structured Placeholder System */
.academic-placeholder-box {
  background: var(--bg-warm-white);
  border: 1.5px dashed rgba(35, 61, 91, 0.22);
  border-radius: var(--radius-lg);
  padding: 28px;
  position: relative;
  transition: border-color var(--transition-fast);
}

.academic-placeholder-box.gold-variant {
  border-color: var(--academic-gold-border);
  background: #FAF8F2;
}

.academic-placeholder-box:hover {
  border-color: var(--academic-navy);
}

.placeholder-badge-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.placeholder-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: var(--bg-surface-blue);
  color: var(--academic-navy);
  border: 1px solid var(--border-subtle);
}

.academic-placeholder-box.gold-variant .placeholder-badge {
  color: var(--academic-gold-dark);
  border-color: var(--academic-gold-border);
  background: var(--bg-ivory);
}

.placeholder-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--academic-navy);
  margin-bottom: 8px;
}

.placeholder-body-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 16px;
}

.placeholder-wireframe-lines {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-top: 14px;
  border-top: 1px solid var(--border-subtle);
}

.wireframe-line {
  height: 8px;
  border-radius: var(--radius-full);
  background: #E2E8F0;
}

.wireframe-line.w-80 { width: 80%; }
.wireframe-line.w-60 { width: 60%; }
.wireframe-line.w-90 { width: 90%; }
.wireframe-line.w-45 { width: 45%; }

/* Layout Variant: Classification (Section 3.1) */
.taxonomy-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.taxonomy-card {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 20px;
  box-shadow: var(--shadow-xs);
}

/* Layout Variant: Reference Tables (Section 3.2) */
.reference-accordion-item {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin-bottom: 12px;
  box-shadow: var(--shadow-xs);
}

.reference-accordion-header {
  padding: 18px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  background: var(--bg-pure-white);
  user-select: none;
  transition: background var(--transition-fast);
}

.reference-accordion-header:hover {
  background: var(--bg-warm-white);
}

.reference-accordion-body {
  padding: 20px 22px;
  border-top: 1px solid var(--border-subtle);
  background: var(--bg-warm-white);
  display: none;
}

.reference-accordion-body.open {
  display: block;
}

/* Layout Variant: Practice Exercises (Section 3.3) */
.interactive-quiz-container {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-sm);
}

.quiz-option-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 18px;
  background: var(--bg-warm-white);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  margin-bottom: 10px;
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--text-primary);
}

.quiz-option-item:hover {
  border-color: var(--academic-navy);
  background: #FFFFFF;
}

.quiz-option-item.selected {
  border-color: var(--academic-navy);
  background: var(--bg-surface-blue);
  color: var(--academic-navy);
  font-weight: 600;
}

/* Layout Variant: Vocabulary Cards (Section 4.1) */
.vocab-cards-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
}

.vocab-card {
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  border-left: 4px solid var(--academic-gold);
  border-radius: var(--radius-md);
  padding: 22px;
  box-shadow: var(--shadow-xs);
}

/* Layout Variant: Before & After Comparisons (Section 4.2) */
.comparison-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-card);
  overflow: hidden;
  margin-bottom: 14px;
  box-shadow: var(--shadow-xs);
}

.comparison-col-informal {
  background: #FFF5F5;
  border-right: 1px solid var(--border-card);
  padding: 20px;
}

.comparison-col-academic {
  background: #FAF8F2;
  padding: 20px;
}

/* Layout Variant: Activity Matching (Section 4.3) */
.activity-slots-container {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.activity-slot-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 16px;
  background: var(--bg-pure-white);
  border: 1px solid var(--border-card);
  padding: 16px 20px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-xs);
}

/* Section Bottom Navigation Controls */
.section-nav-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 32px 0 60px;
  border-top: 1px solid var(--border-subtle);
  margin-top: 40px;
}

.nav-adjacent-link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: color var(--transition-fast);
}

.nav-adjacent-link:hover {
  color: var(--academic-navy);
}

.nav-adjacent-link.right {
  align-items: flex-end;
  text-align: right;
}

.nav-direction-label {
  font-family: var(--font-ui);
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.nav-destination-title {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--academic-navy);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

/* Global Footer */
.main-footer {
  background: var(--bg-warm-white);
  border-top: 1px solid var(--border-subtle);
  padding: 50px 0 34px;
  position: relative;
  z-index: 3;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px;
}

.footer-copy {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.footer-links-list {
  display: flex;
  gap: 22px;
  font-family: var(--font-ui);
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--academic-navy);
}

.footer-links-list a:hover {
  color: var(--academic-gold-dark);
}

/* Entrance Animations */
@keyframes fadeInAcademic {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.view-animated {
  animation: fadeInAcademic 0.32s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Responsive Media Queries */
@media (max-width: 1024px) {
  .grand-hero-content {
    padding: 48px 36px;
    max-width: 600px;
  }

  .teaching-content-wrapper {
    grid-template-columns: 1fr;
  }
  
  .three-sections-cards-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .team-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .nav-menu-desktop {
    display: none;
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .chapters-cards-grid {
    grid-template-columns: 1fr;
  }

  .three-sections-cards-grid {
    grid-template-columns: 1fr;
  }

  .taxonomy-grid,
  .vocab-cards-grid,
  .comparison-card {
    grid-template-columns: 1fr;
  }

  .activity-slot-row {
    grid-template-columns: 1fr;
  }

  .overview-grand-hero {
    min-height: auto;
  }

  .grand-hero-scrim {
    background: linear-gradient(180deg, 
      rgba(255, 255, 255, 0.98) 0%, 
      rgba(255, 255, 255, 0.94) 65%, 
      rgba(255, 255, 255, 0.88) 100%
    );
  }

  .grand-hero-content {
    padding: 42px 28px;
    max-width: 100%;
  }

  .hero-actions-row {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-actions-row .btn {
    width: 100%;
  }
}

@media (max-width: 480px) {
  .team-grid {
    grid-template-columns: 1fr;
  }

  /* Disable decorative floating on mobile for performance & stability */
  .team-card {
    animation: none !important;
  }

  .floating-book-item {
    display: none;
  }

  .section-nav-footer {
    flex-direction: column;
    gap: 20px;
    align-items: stretch;
  }

  .nav-adjacent-link.right {
    align-items: flex-start;
    text-align: left;
  }
}

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