:root {
  --bg-primary: #0a0d14;
  --bg-secondary: #101522;
  --bg-card: rgba(18, 24, 38, 0.7);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-focus: rgba(99, 102, 241, 0.5);
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --accent-light: rgba(99, 102, 241, 0.12);
  --accent-cyan: #06b6d4;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --max-width: 1140px;
  --radius-lg: 16px;
  --radius-md: 10px;
  --radius-sm: 6px;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  position: relative;
  background-image: 
    radial-gradient(circle at 15% 20%, rgba(99, 102, 241, 0.08) 0%, transparent 40%),
    radial-gradient(circle at 85% 60%, rgba(6, 182, 212, 0.06) 0%, transparent 40%);
  background-attachment: fixed;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: #818cf8;
  text-decoration: underline;
}

/* Header & Navbar */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(10, 13, 20, 0.85);
  border-bottom: 1px solid var(--border-color);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.brand-logo {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  background: linear-gradient(135deg, #6366f1, #06b6d4);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 800;
  font-size: 20px;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.brand-text h1 {
  font-size: 1.15rem;
  font-weight: 700;
  color: #fff;
  line-height: 1.2;
}

.brand-text p {
  font-size: 0.75rem;
  color: var(--text-muted);
}

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

.nav-link {
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.2s;
}

.nav-link:hover, .nav-link.active {
  color: #fff;
  background: var(--accent-light);
  text-decoration: none;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all 0.2s ease;
}

.lang-switch:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

/* Hero Section */
.hero {
  padding: 48px 24px 32px;
  max-width: var(--max-width);
  margin: 0 auto;
  text-align: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  background: var(--accent-light);
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: 9999px;
  color: #818cf8;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hero h2 {
  font-size: 2.25rem;
  font-weight: 800;
  color: #fff;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.hero p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 680px;
  margin: 0 auto;
}

.meta-info {
  margin-top: 16px;
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.meta-info span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* Main Container & Layout */
.content-wrapper {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px 24px 80px;
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 40px;
  align-items: start;
}

/* Sidebar Navigation */
.toc-sidebar {
  position: sticky;
  top: 96px;
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 20px;
}

.toc-title {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.toc-item a {
  display: block;
  padding: 7px 12px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 500;
  line-height: 1.4;
  transition: all 0.2s ease;
}

.toc-item a:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.04);
  text-decoration: none;
}

/* Document Body */
.document-body {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

.section-block {
  margin-bottom: 40px;
  scroll-margin-top: 100px;
}

.section-block:last-child {
  margin-bottom: 0;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.section-number {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--accent-light);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.9rem;
  flex-shrink: 0;
}

.section-header h3 {
  font-size: 1.35rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: -0.01em;
}

.document-body p {
  color: #cbd5e1;
  margin-bottom: 14px;
  font-size: 0.98rem;
}

.document-body ul, .document-body ol {
  margin-left: 20px;
  margin-bottom: 16px;
  color: #cbd5e1;
}

.document-body li {
  margin-bottom: 8px;
  padding-left: 4px;
}

.document-body strong {
  color: #fff;
}

/* Highlight & Callout Box */
.callout {
  padding: 16px 20px;
  border-radius: var(--radius-md);
  margin: 20px 0;
  display: flex;
  gap: 14px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
}

.callout.info {
  background: rgba(99, 102, 241, 0.08);
  border-color: rgba(99, 102, 241, 0.25);
}

.callout.warning {
  background: rgba(245, 158, 11, 0.08);
  border-color: rgba(245, 158, 11, 0.25);
}

.callout-icon {
  font-size: 1.25rem;
  line-height: 1;
  flex-shrink: 0;
  margin-top: 2px;
}

.callout-content p {
  margin-bottom: 0;
  font-size: 0.92rem;
  color: #e2e8f0;
}

/* Tables */
.table-wrapper {
  overflow-x: auto;
  margin: 20px 0;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.9rem;
}

th, td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-color);
}

th {
  background: rgba(255, 255, 255, 0.04);
  color: #fff;
  font-weight: 600;
}

td {
  color: #cbd5e1;
}

tr:last-child td {
  border-bottom: none;
}

/* Tab Switcher */
.tab-container {
  display: flex;
  background: rgba(255, 255, 255, 0.04);
  padding: 4px;
  border-radius: var(--radius-md);
  margin: 0 auto 32px;
  max-width: 540px;
  border: 1px solid var(--border-color);
}

.tab-btn {
  flex: 1;
  padding: 10px 16px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s ease;
  text-align: center;
}

.tab-btn.active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.35);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border-color);
  background: var(--bg-secondary);
  padding: 40px 24px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer-content {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
  align-items: center;
}

.footer-links {
  display: flex;
  gap: 20px;
  list-style: none;
}

.footer-links a {
  color: var(--text-secondary);
}

.footer-links a:hover {
  color: #fff;
}

/* Print Styles */
@media print {
  body {
    background: #fff;
    color: #000;
  }
  .site-header, .toc-sidebar, .tab-container, .site-footer, .lang-switch {
    display: none !important;
  }
  .content-wrapper {
    display: block;
    padding: 0;
  }
  .document-body {
    background: transparent;
    border: none;
    box-shadow: none;
    padding: 0;
  }
  .section-header h3 {
    color: #000;
  }
  .document-body p, .document-body li, td, th {
    color: #222;
  }
}

/* Responsive */
@media (max-width: 860px) {
  .content-wrapper {
    grid-template-columns: 1fr;
  }
  .toc-sidebar {
    display: none;
  }
  .document-body {
    padding: 24px 18px;
  }
  .hero h2 {
    font-size: 1.75rem;
  }
}