/* ========================================
   연구 가이드 - 스타일시트
   ======================================== */

/* --- CSS Variables --- */
:root {
  /* Backgrounds (Light default) */
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f7;
  --bg-card: #f0f0f3;
  --bg-card-hover: #e8e8ec;
  --bg-sidebar: #f5f5f7;
  --bg-code: #f5f5f7;
  --bg-hero: #fafafa;

  /* Text (Light default) */
  --text-primary: #1d1d1f;
  --text-secondary: #555566;
  --text-muted: #888899;
  --text-white: #1d1d1f;

  /* Accents */
  --accent-purple: #7c3aed;
  --accent-blue: #4f46e5;
  --accent-cyan: #0891b2;
  --accent-green: #059669;
  --accent-orange: #ea580c;
  --accent-red: #dc2626;
  --accent-pink: #db2777;
  --accent-yellow: #d97706;

  /* Gradients */
  --gradient-main: linear-gradient(135deg, #7c3aed 0%, #4f46e5 50%, #2563eb 100%);
  --gradient-cool: linear-gradient(135deg, #4f46e5 0%, #0891b2 100%);
  --gradient-warm: linear-gradient(135deg, #db2777 0%, #7c3aed 100%);
  --gradient-green: linear-gradient(135deg, #059669 0%, #0891b2 100%);
  --gradient-orange: linear-gradient(135deg, #ea580c 0%, #dc2626 100%);

  /* Borders (Light default) */
  --border-color: #d2d2d8;
  --border-subtle: #e5e5ea;

  /* Layout */
  --sidebar-width: 280px;
  --topbar-height: 56px;
  --progress-height: 3px;
  --content-max-width: 100%;

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  /* Shadows (Light default) */
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.1);
  --shadow-glow-purple: 0 0 30px rgba(124,58,237,0.1);
  --shadow-glow-blue: 0 0 30px rgba(79,70,229,0.1);
  --shadow-glow-cyan: 0 0 30px rgba(8,145,178,0.1);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.6s ease;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--topbar-height) + 24px);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  color-scheme: light dark;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  font-size: 16px;
  overflow-x: hidden;
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
  width: 6px;
}

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

::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* --- Typography --- */
h1, h2, h3, h4 {
  color: var(--text-white);
  font-weight: 700;
  line-height: 1.3;
}

h2 {
  font-size: clamp(1.8rem, 3vw, 2.5rem);
  margin-bottom: 1rem;
}

h3 {
  font-size: clamp(1.2rem, 2vw, 1.4rem);
  margin-bottom: 0.75rem;
  margin-top: 2.5rem;
}

h4 {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
  margin-top: 1.5rem;
  color: var(--text-primary);
}

p {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

a {
  color: var(--accent-cyan);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--accent-purple);
}

strong {
  color: var(--text-primary);
  font-weight: 600;
}

code {
  font-family: var(--font-mono);
  background: var(--bg-code);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
  color: var(--accent-cyan);
}

blockquote {
  border-left: 3px solid var(--accent-purple);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  background: rgba(167,139,250,0.05);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--text-secondary);
  font-style: italic;
}

ul, ol {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
  color: var(--text-secondary);
}

li {
  margin-bottom: 0.4rem;
}

li::marker {
  color: var(--accent-purple);
}

/* --- Gradient Text --- */
.gradient-text {
  background: var(--gradient-main);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.gradient-text-cool {
  background: var(--gradient-cool);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.gradient-text-warm {
  background: var(--gradient-warm);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* --- Progress Bar --- */
#progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: var(--progress-height);
  background: var(--gradient-main);
  z-index: 1001;
  width: 0%;
  transition: width 0.1s linear;
}

/* --- Top Bar --- */
#topbar {
  position: fixed;
  top: var(--progress-height);
  left: 0;
  right: 0;
  height: var(--topbar-height);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  z-index: 999;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-subtle);
  transition: all var(--transition-normal);
}

#topbar.scrolled {
  background: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
}

.menu-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-size: 1.3rem;
  cursor: pointer;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  margin-right: 1rem;
  line-height: 1;
}

.menu-toggle:hover {
  background: var(--bg-card);
  border-color: var(--accent-purple);
}

.site-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  flex: 1;
}

.topbar-right {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-left: auto;
}

#theme-toggle {
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

#theme-toggle:hover {
  background: rgba(167,139,250,0.1);
}

.admin-link {
  color: var(--text-muted);
  font-size: 1.1rem;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  text-decoration: none;
  opacity: 0.4;
  flex-shrink: 0;
}

.admin-link:hover {
  opacity: 1;
  color: var(--accent-purple);
  background: rgba(167,139,250,0.1);
}

/* --- Sidebar --- */
#sidebar {
  position: fixed;
  top: calc(var(--topbar-height) + var(--progress-height));
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--topbar-height) - var(--progress-height));
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-subtle);
  overflow-y: auto;
  padding: 1rem 0;
  z-index: 998;
  transition: transform var(--transition-normal);
}

#sidebar::-webkit-scrollbar {
  width: 4px;
}

#search-box {
  padding: 0 1rem 1rem;
  position: sticky;
  top: 0;
  background: var(--bg-sidebar);
  z-index: 1;
}

#search-input {
  width: 100%;
  padding: 8px 12px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  outline: none;
  transition: border-color var(--transition-fast);
}

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

#search-input:focus {
  border-color: var(--accent-purple);
  box-shadow: 0 0 0 3px rgba(167,139,250,0.1);
}

#toc-container {
  padding: 0 0.5rem;
}

.toc-group-label {
  display: block;
  padding: 0.6rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-top: 0.5rem;
}

.toc-item {
  display: block;
  padding: 0.4rem 0.75rem 0.4rem 1.2rem;
  font-size: 0.82rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  border-left: 2px solid transparent;
  margin: 1px 0;
}

.toc-item:hover {
  color: var(--text-primary);
  background: rgba(167,139,250,0.05);
}

.toc-item.active {
  color: var(--accent-purple);
  background: rgba(167,139,250,0.08);
  border-left-color: var(--accent-purple);
  font-weight: 500;
}

.toc-item.toc-h3 {
  padding-left: 2rem;
  font-size: 0.78rem;
}

.toc-hidden {
  display: none;
}

.toc-no-results {
  padding: 1rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* --- Sidebar Overlay --- */
#sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 997;
  backdrop-filter: blur(4px);
}

#sidebar-overlay.visible {
  display: block;
}

/* --- Main Content --- */
#main-content {
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  padding-top: calc(var(--topbar-height) + var(--progress-height));
}

#content {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 2rem 2.5rem 4rem;
  overflow-x: hidden;
}

.md-content {
  overflow-x: hidden;
}

/* --- Section Styles --- */
.section {
  margin-bottom: 5rem;
  padding-top: 1rem;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-subtle);
}

.section-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  font-size: 1.3rem;
  font-weight: 800;
  flex-shrink: 0;
}

.section-number.purple { background: rgba(167,139,250,0.15); color: var(--accent-purple); }
.section-number.blue { background: rgba(99,102,241,0.15); color: var(--accent-blue); }
.section-number.cyan { background: rgba(34,211,238,0.15); color: var(--accent-cyan); }
.section-number.green { background: rgba(52,211,153,0.15); color: var(--accent-green); }
.section-number.orange { background: rgba(251,146,60,0.15); color: var(--accent-orange); }
.section-number.pink { background: rgba(244,114,182,0.15); color: var(--accent-pink); }

.section-desc {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 2.5rem;
  line-height: 1.7;
}

/* --- Hero Section --- */
.hero-section {
  text-align: center;
  padding: 6rem 0 4rem;
  position: relative;
}

.hero-section::before {
  content: '';
  position: absolute;
  top: -20%;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(99,102,241,0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero-badge {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(167,139,250,0.1);
  border: 1px solid rgba(167,139,250,0.2);
  border-radius: 50px;
  font-size: 0.85rem;
  color: var(--accent-purple);
  margin-bottom: 1.5rem;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1.5rem;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
}

.hero-stat {
  text-align: center;
  padding: 1.2rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  min-width: 140px;
  backdrop-filter: blur(10px);
  transition: all var(--transition-normal);
}

.hero-stat:hover {
  border-color: var(--accent-purple);
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow-purple);
}

.hero-stat-number {
  font-size: 1.8rem;
  font-weight: 800;
  display: block;
  margin-bottom: 0.3rem;
}

.hero-stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.hero-cta {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-normal);
  text-decoration: none;
  border: none;
}

.btn-primary {
  background: var(--gradient-main);
  color: white;
  box-shadow: 0 4px 15px rgba(99,102,241,0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99,102,241,0.4);
  color: white;
}

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

.btn-secondary:hover {
  border-color: var(--accent-purple);
  background: rgba(167,139,250,0.05);
  color: var(--accent-purple);
}

/* --- Card Component --- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(260px, 100%), 1fr));
  gap: 1.2rem;
  margin: 1.5rem 0;
  max-width: 100%;
}

.card-grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(min(240px, 100%), 1fr));
}

.card-grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(min(320px, 100%), 1fr));
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--gradient-main);
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.card:hover {
  border-color: rgba(167,139,250,0.3);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

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

.card-icon {
  font-size: 2rem;
  margin-bottom: 0.8rem;
  display: block;
}

.card-title {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-white);
  margin-bottom: 0.5rem;
}

.card-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.card-tag {
  display: inline-block;
  padding: 3px 10px;
  font-size: 0.75rem;
  border-radius: 50px;
  margin-top: 0.8rem;
  margin-right: 0.3rem;
  font-weight: 500;
}

.tag-purple { background: rgba(167,139,250,0.15); color: var(--accent-purple); }
.tag-blue { background: rgba(99,102,241,0.15); color: var(--accent-blue); }
.tag-cyan { background: rgba(34,211,238,0.15); color: var(--accent-cyan); }
.tag-green { background: rgba(52,211,153,0.15); color: var(--accent-green); }
.tag-orange { background: rgba(251,146,60,0.15); color: var(--accent-orange); }
.tag-red { background: rgba(248,113,113,0.15); color: var(--accent-red); }
.tag-pink { background: rgba(244,114,182,0.15); color: var(--accent-pink); }
.tag-yellow { background: rgba(251,191,36,0.15); color: var(--accent-yellow); }

/* Card with accent border */
.card.accent-purple { border-left: 3px solid var(--accent-purple); }
.card.accent-blue { border-left: 3px solid var(--accent-blue); }
.card.accent-cyan { border-left: 3px solid var(--accent-cyan); }
.card.accent-green { border-left: 3px solid var(--accent-green); }
.card.accent-orange { border-left: 3px solid var(--accent-orange); }

/* --- Glass Card --- */
.glass {
  background: rgba(240, 240, 243, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(0, 0, 0, 0.06);
}

[data-theme="dark"] .glass {
  background: rgba(22, 22, 31, 0.6);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

/* --- Tab System --- */
.tab-container {
  margin: 1.5rem 0;
  max-width: 100%;
}

.tab-buttons {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.2rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.tab-buttons::-webkit-scrollbar {
  display: none;
}

.tab-btn {
  padding: 10px 20px;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  margin-bottom: -1px;
}

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

.tab-btn.active {
  color: var(--accent-purple);
  border-bottom-color: var(--accent-purple);
}

.tab-content {
  display: none;
  animation: fadeIn 0.3s ease;
}

.tab-content.active {
  display: block;
}

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

/* --- Comparison Table --- */
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.9rem;
}

.comparison-table thead {
  position: sticky;
  top: calc(var(--topbar-height) + var(--progress-height));
}

.comparison-table th {
  background: var(--bg-card);
  color: var(--text-white);
  font-weight: 600;
  padding: 12px 16px;
  text-align: left;
  border-bottom: 2px solid var(--accent-purple);
  font-size: 0.85rem;
}

.comparison-table td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  vertical-align: top;
}

.comparison-table tr:hover td {
  background: rgba(167,139,250,0.03);
}

.comparison-table .highlight {
  color: var(--accent-cyan);
  font-weight: 500;
}

/* --- Pipeline Diagram --- */
.pipeline {
  display: flex;
  align-items: center;
  gap: 0;
  margin: 2rem 0;
  padding: 1rem 0;
  flex-wrap: wrap;
  justify-content: center;
  max-width: 100%;
}

.pipeline-step {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  min-width: 100px;
  max-width: 140px;
  padding: 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  transition: all var(--transition-normal);
  flex: 1 1 100px;
}

.pipeline-step:hover {
  border-color: var(--accent-purple);
  transform: translateY(-2px);
}

.pipeline-step-icon {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.pipeline-step-title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-white);
  margin-bottom: 0.3rem;
}

.pipeline-step-desc {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.pipeline-arrow {
  font-size: 1.2rem;
  color: var(--accent-purple);
  flex-shrink: 0;
  padding: 0 0.3rem;
}

/* --- Timeline --- */
.timeline {
  position: relative;
  padding-left: 2rem;
  margin: 2rem 0;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent-purple), var(--accent-cyan), var(--accent-green));
}

.timeline-item {
  position: relative;
  margin-bottom: 2rem;
  padding-left: 1.5rem;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -2rem;
  top: 6px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--bg-primary);
  border: 3px solid var(--accent-purple);
  z-index: 1;
}

.timeline-item:nth-child(2)::before { border-color: var(--accent-blue); }
.timeline-item:nth-child(3)::before { border-color: var(--accent-cyan); }
.timeline-item:nth-child(4)::before { border-color: var(--accent-green); }
.timeline-item:nth-child(5)::before { border-color: var(--accent-orange); }

.timeline-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent-purple);
  margin-bottom: 0.3rem;
}

.timeline-title {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-white);
  margin-bottom: 0.4rem;
}

.timeline-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* --- Highlight Box --- */
.highlight-box {
  padding: 1.2rem 1.5rem;
  border-radius: var(--radius-md);
  margin: 1.5rem 0;
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}

.highlight-box-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.highlight-box-content {
  flex: 1;
  min-width: 0;
  overflow-wrap: break-word;
}

.highlight-box-content p {
  margin-bottom: 0.3rem;
}

.highlight-box.tip {
  background: rgba(52,211,153,0.08);
  border: 1px solid rgba(52,211,153,0.2);
}

.highlight-box.warning {
  background: rgba(251,146,60,0.08);
  border: 1px solid rgba(251,146,60,0.2);
}

.highlight-box.info {
  background: rgba(99,102,241,0.08);
  border: 1px solid rgba(99,102,241,0.2);
}

.highlight-box.important {
  background: rgba(248,113,113,0.08);
  border: 1px solid rgba(248,113,113,0.2);
}

/* --- Code Block --- */
.code-block {
  background: var(--bg-code);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.2rem 1.5rem;
  margin: 1rem 0;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--text-primary);
}

.code-block .comment { color: var(--text-muted); }
.code-block .keyword { color: var(--accent-purple); }
.code-block .string { color: var(--accent-green); }
.code-block .function { color: var(--accent-cyan); }
.code-block .number { color: var(--accent-orange); }

/* --- Formula Box --- */
.formula-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.2rem 1.5rem;
  margin: 1rem 0;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--accent-cyan);
}

/* --- List Check --- */
.check-list {
  list-style: none;
  padding-left: 0;
}

.check-list label {
  display: block;
  padding: 0.5rem 0;
  padding-left: 0.3rem;
  line-height: 1.6;
  cursor: pointer;
}

.check-list label input[type="checkbox"] {
  margin-right: 0.5rem;
  accent-color: var(--accent-green);
}

.check-list li {
  padding: 0.4rem 0;
  padding-left: 1.8rem;
  position: relative;
}

.check-list li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--accent-green);
  font-weight: 700;
}

/* --- Do/Don't Comparison --- */
.do-dont {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
  margin: 1.5rem 0;
}

.do-box, .dont-box {
  padding: 1.5rem;
  border-radius: var(--radius-md);
}

.do-box {
  background: rgba(52,211,153,0.06);
  border: 1px solid rgba(52,211,153,0.2);
}

.dont-box {
  background: rgba(248,113,113,0.06);
  border: 1px solid rgba(248,113,113,0.2);
}

.do-box h4 { color: var(--accent-green); }
.dont-box h4 { color: var(--accent-red); }

.do-box li::marker { color: var(--accent-green); }
.dont-box li::marker { color: var(--accent-red); }

/* --- Scroll Reveal --- */
/* 콘텐츠는 항상 보이되, 뷰포트 진입 시 부드러운 등장 효과 */
.reveal {
  opacity: 1;
  transform: translateY(0);
}

@keyframes revealUp {
  from {
    opacity: 0.3;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.reveal.animated {
  animation: revealUp 0.6s ease-out forwards;
}

.reveal.animated[data-delay="1"] { animation-delay: 0.1s; }
.reveal.animated[data-delay="2"] { animation-delay: 0.2s; }
.reveal.animated[data-delay="3"] { animation-delay: 0.3s; }
.reveal.animated[data-delay="4"] { animation-delay: 0.4s; }

/* 카드, 하이라이트 박스 등에 hover 시 부드러운 효과 */
.section-header {
  transition: opacity 0.4s ease;
}

.subsection {
  transition: opacity 0.4s ease;
}

/* --- Sub-section divider --- */
.subsection {
  margin-top: 3rem;
  margin-bottom: 2rem;
}

.subsection-title {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  font-size: 1.25rem;
}

.subsection-icon {
  font-size: 1.3rem;
}

/* --- Markdown Content --- */
.md-content {
  margin-top: 1rem;
  color: var(--text-primary);
}

.md-content p,
.md-content li,
.md-content span,
.md-content div,
.md-content label {
  color: var(--text-primary);
}

.md-content strong {
  color: var(--text-white);
}

.md-content a {
  color: var(--accent-purple);
}

.md-content h1, .md-content h2, .md-content h3, .md-content h4 {
  margin-top: 1.5rem;
}

.md-content h1:first-child, .md-content h2:first-child,
.md-content h3:first-child, .md-content h4:first-child {
  margin-top: 0;
}

.md-content img {
  max-width: 100%;
  border-radius: var(--radius-md);
  margin: 1rem 0;
}

.md-content pre {
  background: var(--bg-code);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.2rem 1.5rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  margin: 1rem 0;
}

.md-content pre code {
  background: none;
  padding: 0;
  font-size: inherit;
  color: var(--text-primary);
}

.md-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: 0.9rem;
}

.md-content th {
  background: var(--bg-card);
  color: var(--text-white);
  font-weight: 600;
  padding: 10px 16px;
  text-align: left;
  border-bottom: 2px solid var(--accent-purple);
}

.md-content td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.md-content tr:hover td {
  background: rgba(167,139,250,0.03);
}

.md-content hr {
  border: none;
  border-top: 1px solid var(--border-color);
  margin: 2rem 0;
}

/* --- Footer --- */
.site-footer {
  text-align: center;
  padding: 3rem 0;
  border-top: 1px solid var(--border-subtle);
  margin-top: 4rem;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.footer-heart {
  color: var(--accent-red);
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 900px) {
  #sidebar {
    transform: translateX(-100%);
    z-index: 1000;
    box-shadow: none;
  }

  #sidebar.open {
    transform: translateX(0);
    box-shadow: var(--shadow-lg);
  }

  .menu-toggle {
    display: block;
  }

  #main-content {
    margin-left: 0;
  }

  #content {
    padding: 1.5rem;
  }

}

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

  .card-grid-2 {
    grid-template-columns: 1fr;
  }

  .hero-stats {
    flex-direction: column;
    align-items: center;
    gap: 1rem;
  }

  .hero-stat {
    min-width: 200px;
  }

  .hero-title {
    font-size: 2rem;
  }

  .pipeline {
    flex-direction: column;
    align-items: stretch;
  }

  .pipeline-arrow {
    transform: rotate(90deg);
    text-align: center;
    padding: 0.3rem 0;
  }

  .pipeline-step {
    min-width: auto;
  }

  .do-dont {
    grid-template-columns: 1fr;
  }

  .comparison-table {
    font-size: 0.8rem;
  }

  .comparison-table th,
  .comparison-table td {
    padding: 8px 10px;
  }

  .tab-btn {
    padding: 8px 14px;
    font-size: 0.82rem;
  }
}

@media (max-width: 480px) {
  .hero-section {
    padding: 3rem 0 2rem;
  }

  .hero-title {
    font-size: 1.6rem;
  }

  .hero-subtitle {
    font-size: 0.95rem;
  }

  .section-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }

  h2 {
    font-size: 1.5rem;
  }

  h3 {
    font-size: 1.1rem;
  }

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

/* --- Print --- */
@media print {
  #sidebar, #topbar, #progress-bar, #sidebar-overlay, .menu-toggle {
    display: none !important;
  }

  #main-content {
    margin-left: 0;
  }

  body {
    background: white;
    color: #333;
  }

  .card, .highlight-box, .pipeline-step {
    border: 1px solid #ddd;
    background: white;
  }
}

/* Chrome 강제 다크모드 무력화는 color-scheme: only dark로 처리 */

/* ========================================
   Dark Mode (data-theme="dark")
   ======================================== */
[data-theme="dark"] {
  --bg-primary: #0a0a0f;
  --bg-secondary: #111118;
  --bg-card: #16161f;
  --bg-card-hover: #1c1c28;
  --bg-sidebar: #0d0d14;
  --bg-code: #0d1117;
  --bg-hero: #080810;

  --text-primary: #e8e8ed;
  --text-secondary: #9898a8;
  --text-muted: #6a6a7a;
  --text-white: #ffffff;

  --accent-purple: #a78bfa;
  --accent-blue: #6366f1;
  --accent-cyan: #22d3ee;
  --accent-green: #34d399;
  --accent-orange: #fb923c;
  --accent-red: #f87171;
  --accent-pink: #f472b6;
  --accent-yellow: #fbbf24;

  --gradient-main: linear-gradient(135deg, #a78bfa 0%, #6366f1 50%, #3b82f6 100%);
  --gradient-cool: linear-gradient(135deg, #6366f1 0%, #22d3ee 100%);
  --gradient-warm: linear-gradient(135deg, #f472b6 0%, #a78bfa 100%);

  --border-color: #2a2a3a;
  --border-subtle: #1e1e2e;

  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
}

[data-theme="dark"] body {
  background-color: #0a0a0f;
  color: #e8e8ed;
}

[data-theme="dark"] #topbar {
  background: rgba(10, 10, 15, 0.8);
  border-bottom-color: transparent;
}

[data-theme="dark"] #topbar.scrolled {
  background: rgba(10, 10, 15, 0.95);
  border-bottom-color: #1e1e2e;
}

[data-theme="dark"] .site-title {
  color: #9898a8;
}

[data-theme="dark"] #sidebar {
  background: #0d0d14;
  border-right-color: #1e1e2e;
}

[data-theme="dark"] .toc-item {
  color: #9898a8;
}

[data-theme="dark"] .toc-item:hover,
[data-theme="dark"] .toc-item.active {
  color: #a78bfa;
  background: rgba(167,139,250,0.1);
}

[data-theme="dark"] .toc-group-label {
  color: #e8e8ed;
}

[data-theme="dark"] #search-input {
  background: #16161f;
  color: #e8e8ed;
  border-color: #2a2a3a;
}

[data-theme="dark"] .hero-section::before {
  background: radial-gradient(circle, rgba(99,102,241,0.08) 0%, transparent 70%);
}

[data-theme="dark"] .hero-title,
[data-theme="dark"] .hero-subtitle {
  color: #e8e8ed;
}

[data-theme="dark"] .hero-badge {
  background: rgba(167,139,250,0.1);
  border-color: rgba(167,139,250,0.2);
}

[data-theme="dark"] h1, [data-theme="dark"] h2,
[data-theme="dark"] h3, [data-theme="dark"] h4 {
  color: #ffffff;
}

[data-theme="dark"] .card {
  background: #16161f;
  border-color: #2a2a3a;
}

[data-theme="dark"] .card:hover {
  border-color: rgba(167,139,250,0.3);
  box-shadow: 0 4px 16px rgba(0,0,0,0.4);
}

[data-theme="dark"] .card-title {
  color: #ffffff;
}

[data-theme="dark"] .card-desc {
  color: #9898a8;
}

[data-theme="dark"] .highlight-box.tip {
  background: rgba(52,211,153,0.06);
  border-color: rgba(52,211,153,0.25);
}

[data-theme="dark"] .highlight-box.warning {
  background: rgba(251,146,60,0.06);
  border-color: rgba(251,146,60,0.25);
}

[data-theme="dark"] .highlight-box.info {
  background: rgba(99,102,241,0.06);
  border-color: rgba(99,102,241,0.25);
}

[data-theme="dark"] .highlight-box.important {
  background: rgba(248,113,113,0.06);
  border-color: rgba(248,113,113,0.25);
}

[data-theme="dark"] .tab-btn {
  color: #6a6a7a;
}

[data-theme="dark"] .tab-btn.active {
  color: #a78bfa;
  border-bottom-color: #a78bfa;
}

[data-theme="dark"] .pipeline-step {
  background: #16161f;
  border-color: #2a2a3a;
}

[data-theme="dark"] .pipeline-step:hover {
  border-color: #a78bfa;
}

[data-theme="dark"] .timeline::before {
  background: linear-gradient(to bottom, #a78bfa, #6366f1, #34d399);
}

[data-theme="dark"] .do-box {
  background: rgba(52,211,153,0.05);
  border-color: rgba(52,211,153,0.25);
}

[data-theme="dark"] .dont-box {
  background: rgba(248,113,113,0.05);
  border-color: rgba(248,113,113,0.25);
}

[data-theme="dark"] .md-content p,
[data-theme="dark"] .md-content li,
[data-theme="dark"] .md-content span,
[data-theme="dark"] .md-content div,
[data-theme="dark"] .md-content label {
  color: #e8e8ed;
}

[data-theme="dark"] .md-content strong {
  color: #ffffff;
}

[data-theme="dark"] .md-content a {
  color: #a78bfa;
}

[data-theme="dark"] .md-content pre {
  background: #0d1117;
  border-color: #2a2a3a;
}

[data-theme="dark"] .md-content pre code {
  color: #e8e8ed;
}

[data-theme="dark"] .md-content th {
  background: #16161f;
  color: #ffffff;
}

[data-theme="dark"] .md-content td {
  color: #9898a8;
  border-bottom-color: #1e1e2e;
}

[data-theme="dark"] .md-content hr {
  border-top-color: #2a2a3a;
}

[data-theme="dark"] .section-number.purple { background: rgba(167,139,250,0.15); }
[data-theme="dark"] .section-number.blue { background: rgba(99,102,241,0.15); }
[data-theme="dark"] .section-number.cyan { background: rgba(34,211,238,0.15); }
[data-theme="dark"] .section-number.green { background: rgba(52,211,153,0.15); }
[data-theme="dark"] .section-number.orange { background: rgba(251,146,60,0.15); }
[data-theme="dark"] .section-number.pink { background: rgba(244,114,182,0.15); }

[data-theme="dark"] .section-desc {
  color: #9898a8;
}

[data-theme="dark"] .hero-stat {
  background: rgba(22, 22, 31, 0.6);
  border-color: rgba(255,255,255,0.05);
}

[data-theme="dark"] #progress-bar {
  background: var(--gradient-main);
}

[data-theme="dark"] .gradient-text {
  background: linear-gradient(135deg, #a78bfa 0%, #6366f1 50%, #3b82f6 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

[data-theme="dark"] .btn {
  background: linear-gradient(135deg, #a78bfa, #6366f1);
  color: #ffffff;
}

[data-theme="dark"] .btn-secondary {
  background: transparent;
  color: #e8e8ed;
  border-color: #2a2a3a;
}

[data-theme="dark"] .admin-link {
  color: #6a6a7a;
}

[data-theme="dark"] #theme-toggle:hover {
  background: rgba(167,139,250,0.1);
}

[data-theme="dark"] ::-webkit-scrollbar-track {
  background: #0a0a0f;
}

[data-theme="dark"] ::-webkit-scrollbar-thumb {
  background: #2a2a3a;
}

[data-theme="dark"] .check-list label {
  color: #e8e8ed;
}

[data-theme="dark"] .site-footer {
  color: #6a6a7a;
  border-top-color: #1e1e2e;
}