/* ==========================================================================
   TYPOGRAPHY LAB - Modern Interactive Typography Research Website
   ========================================================================== */

@import url('https://cdn.jsdelivr.net/gh/orioncactus/pretendard/dist/web/static/pretendard.css');
@import url('https://fonts.googleapis.com/css2?family=Cinzel:wght@400;700;900&family=Courier+Prime:ital,wght@0,400;0,700;1,400&family=Inter:wght@300;400;500;600;700;800;900&family=Nanum+Myeongjo:wght@400;700;800&family=Playfair+Display:ital,wght@0,400;0,600;0,800;1,400&family=Montserrat:wght@400;600;800;900&family=Pacifico&display=swap');

:root {
  /* Color Palette - Light Mode */
  --bg-primary: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-elevated: #ffffff;
  --bg-secondary: #f1f5f9;
  --bg-tertiary: #e2e8f0;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-inverse: #ffffff;

  --accent-primary: #2563eb;
  --accent-primary-hover: #1d4ed8;
  --accent-secondary: #7c3aed;
  --accent-emerald: #059669;
  --accent-amber: #d97706;
  --accent-rose: #e11d48;
  
  --border-color: #e2e8f0;
  --border-focus: #3b82f6;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 25px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 35px -5px rgba(0, 0, 0, 0.12), 0 8px 10px -6px rgba(0, 0, 0, 0.06);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 9999px;

  --font-sans: 'Pretendard', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-serif: 'Playfair Display', 'Nanum Myeongjo', Georgia, serif;
  --font-mono: 'Courier Prime', Menlo, monospace;

  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
  --transition-slow: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

[data-theme="dark"] {
  --bg-primary: #090d16;
  --bg-surface: #111827;
  --bg-surface-elevated: #1f2937;
  --bg-secondary: #172033;
  --bg-tertiary: #1f293d;

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --text-inverse: #0f172a;

  --accent-primary: #3b82f6;
  --accent-primary-hover: #60a5fa;
  --accent-secondary: #a78bfa;
  --accent-emerald: #10b981;
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;

  --border-color: #1e293b;
  --border-focus: #60a5fa;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.5);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.7);
}

/* Base Styles */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
}

/* Layout */
.container {
  width: 100%;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header & Nav */
header.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(248, 250, 252, 0.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-color);
  transition: all var(--transition-normal);
}

[data-theme="dark"] header.site-header {
  background: rgba(9, 13, 22, 0.85);
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 800;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.brand-badge {
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  color: white;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 8px;
  list-style: none;
}

.nav-link {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

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

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.btn-icon {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 42px;
  height: 42px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1.1rem;
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  background: var(--bg-tertiary);
  transform: translateY(-1px);
}

.mobile-menu-btn {
  display: none;
}

/* Hero Section */
.hero-section {
  padding: 90px 0 60px;
  position: relative;
  overflow: hidden;
}

.hero-badge-container {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--accent-primary);
  margin-bottom: 24px;
}

.hero-title {
  font-size: clamp(2.4rem, 5vw, 4.2rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
  color: var(--text-primary);
}

.hero-title .gradient-text {
  background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 760px;
  line-height: 1.75;
  margin-bottom: 36px;
}

.hero-stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin-top: 50px;
}

.stat-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent-primary);
}

.stat-num {
  font-size: 2.4rem;
  font-weight: 900;
  color: var(--accent-primary);
  line-height: 1.1;
  margin-bottom: 6px;
  font-feature-settings: "tnum";
}

.stat-label {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.stat-sub {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Section Common */
.section {
  padding: 80px 0;
  border-top: 1px solid var(--border-color);
}

.section-header {
  margin-bottom: 48px;
}

.section-kicker {
  font-size: 0.85rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent-primary);
  margin-bottom: 8px;
}

.section-title {
  font-size: clamp(1.8rem, 3.5vw, 2.6rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 720px;
}

/* Cards & Panels */
.card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 32px;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

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

/* Anatomy Section */
.anatomy-layout {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 32px;
  align-items: start;
}

.svg-display-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  text-align: center;
}

.svg-display-card svg {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-sm);
}

.anatomy-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.anatomy-item {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.anatomy-item:hover, .anatomy-item.active {
  background: var(--bg-secondary);
  transform: translateX(4px);
}

.anatomy-item.ascender { border-left-color: var(--accent-rose); }
.anatomy-item.capheight { border-left-color: var(--accent-amber); }
.anatomy-item.xheight { border-left-color: var(--accent-primary); }
.anatomy-item.baseline { border-left-color: var(--accent-emerald); }
.anatomy-item.descender { border-left-color: var(--accent-secondary); }

.anatomy-item-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}

.anatomy-name {
  font-weight: 700;
  font-size: 1.05rem;
}

.anatomy-pill {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: var(--radius-full);
}

/* Classification Grid */
.class-tabs {
  display: flex;
  gap: 12px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}

.tab-btn {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  padding: 10px 20px;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.tab-btn:hover, .tab-btn.active {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
}

.class-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.class-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-normal);
}

.class-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-primary);
}

.specimen-preview {
  font-size: 3rem;
  line-height: 1.2;
  margin: 16px 0;
  min-height: 80px;
  display: flex;
  align-items: center;
}

.specimen-serif { font-family: var(--font-serif); }
.specimen-sans { font-family: var(--font-sans); }
.specimen-slab { font-family: var(--font-mono); }
.specimen-script { font-family: 'Pacifico', cursive; }

/* Interactive Typography Lab */
.lab-container {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 32px;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-md);
}

.lab-controls {
  display: flex;
  flex-direction: column;
  gap: 24px;
  border-right: 1px solid var(--border-color);
  padding-right: 32px;
}

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

.control-label {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-primary);
}

.control-val {
  color: var(--accent-primary);
  font-feature-settings: "tnum";
}

input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-full);
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-primary);
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

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

.align-btn {
  flex: 1;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 8px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.align-btn.active, .align-btn:hover {
  background: var(--accent-primary);
  color: white;
  border-color: var(--accent-primary);
}

.lab-preview-area {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.live-editable-text {
  background: var(--bg-secondary);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px;
  min-height: 280px;
  outline: none;
  transition: all var(--transition-fast);
}

.live-editable-text:focus {
  border-color: var(--border-focus);
  background: var(--bg-surface);
}

.cpl-meter {
  margin-top: 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 18px;
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
}

.cpl-status-good {
  color: var(--accent-emerald);
}

.cpl-status-warn {
  color: var(--accent-amber);
}

/* Font Pairing Studio */
.pairing-studio {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.pair-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 32px;
  transition: all var(--transition-normal);
}

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

.pair-header-sample {
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: 12px;
  line-height: 1.2;
}

.pair-body-sample {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.pair-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 800;
  text-transform: uppercase;
  background: var(--bg-secondary);
  color: var(--accent-primary);
  padding: 4px 10px;
  border-radius: var(--radius-full);
  margin-bottom: 16px;
}

/* Timeline Section */
.timeline-container {
  position: relative;
  max-width: 900px;
  margin: 0 auto;
  padding: 20px 0;
}

.timeline-container::after {
  content: '';
  position: absolute;
  width: 4px;
  background: var(--border-color);
  top: 0;
  bottom: 0;
  left: 50%;
  margin-left: -2px;
  border-radius: var(--radius-full);
}

.timeline-block {
  padding: 10px 40px;
  position: relative;
  width: 50%;
}

.timeline-block.left {
  left: 0;
}

.timeline-block.right {
  left: 50%;
}

.timeline-dot {
  position: absolute;
  width: 20px;
  height: 20px;
  background: var(--accent-primary);
  border: 4px solid var(--bg-surface);
  top: 24px;
  border-radius: 50%;
  z-index: 10;
  box-shadow: var(--shadow-sm);
}

.timeline-block.left .timeline-dot {
  right: -10px;
}

.timeline-block.right .timeline-dot {
  left: -10px;
}

.timeline-content {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  padding: 24px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}

.timeline-content:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent-primary);
}

.timeline-year {
  font-size: 0.85rem;
  font-weight: 800;
  color: var(--accent-primary);
  margin-bottom: 6px;
}

.timeline-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.timeline-text {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* Video Grid */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.video-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-primary);
}

.video-thumb-wrapper {
  position: relative;
  width: 100%;
  padding-top: 56.25%; /* 16:9 Aspect Ratio */
  background: #000;
  overflow: hidden;
}

.video-thumb-wrapper iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

.video-body {
  padding: 20px;
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.video-tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-rose);
  text-transform: uppercase;
  margin-bottom: 6px;
}

.video-title {
  font-size: 1.05rem;
  font-weight: 700;
  line-height: 1.35;
  margin-bottom: 8px;
}

.video-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.video-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-primary);
  transition: all var(--transition-fast);
}

.video-btn:hover {
  background: var(--accent-primary);
  color: white;
}

/* Checklist & Quiz Section */
.tools-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}

.checklist-group {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 20px;
}

.check-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  background: var(--bg-secondary);
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.check-item input[type="checkbox"] {
  width: 18px;
  height: 18px;
  margin-top: 2px;
  accent-color: var(--accent-primary);
  cursor: pointer;
}

.check-item span {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* Quiz Box */
.quiz-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px;
}

.quiz-option {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  margin-bottom: 10px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
}

.quiz-option:hover {
  border-color: var(--accent-primary);
  background: var(--bg-tertiary);
}

.quiz-option.correct {
  background: #dcfce7;
  border-color: #22c55e;
  color: #15803d;
}

.quiz-option.incorrect {
  background: #fee2e2;
  border-color: #ef4444;
  color: #b91c1c;
}

/* Footer */
footer.site-footer {
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 60px 0 30px;
  margin-top: 80px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Responsive Media Queries */
@media (max-width: 992px) {
  .anatomy-layout, .lab-container, .pairing-studio, .tools-layout {
    grid-template-columns: 1fr;
  }
  
  .lab-controls {
    border-right: none;
    border-bottom: 1px solid var(--border-color);
    padding-right: 0;
    padding-bottom: 24px;
  }

  .timeline-container::after {
    left: 31px;
  }

  .timeline-block {
    width: 100%;
    padding-left: 70px;
    padding-right: 25px;
  }

  .timeline-block.right {
    left: 0;
  }

  .timeline-block.left .timeline-dot,
  .timeline-block.right .timeline-dot {
    left: 21px;
  }
}

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

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

  .footer-grid {
    grid-template-columns: 1fr;
  }
}