:root {
  --brand: #0d8a9a;
  --brand-dark: #0a6b77;
  --brand-soft: #e6f5f7;
  --sidebar-bg: #1e293b;
  --sidebar-text: #cbd5e1;
  --sidebar-active: #38bdf8;
  --page-bg: #f1f5f9;
  --content-bg: #ffffff;
  --text: #1e293b;
  --muted: #64748b;
  --border: #e2e8f0;
  --warn-bg: #fff7ed;
  --warn-border: #fdba74;
  --info-bg: #eff6ff;
  --info-border: #93c5fd;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  color: var(--text);
  background: var(--page-bg);
  line-height: 1.6;
}

.layout {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 300px;
  flex-shrink: 0;
  background: var(--sidebar-bg);
  color: var(--sidebar-text);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 1.25rem 0 2rem;
  z-index: 20;
}

.sidebar-brand {
  padding: 0 1.25rem 1.25rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  margin-bottom: 1rem;
}

.sidebar-brand a {
  color: #fff;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
  display: block;
}

.sidebar-brand span {
  display: block;
  font-size: 0.75rem;
  color: #94a3b8;
  font-weight: 400;
  margin-top: 0.25rem;
}

.sidebar nav a {
  display: block;
  padding: 0.4rem 1.25rem;
  color: var(--sidebar-text);
  text-decoration: none;
  font-size: 0.875rem;
  border-left: 3px solid transparent;
}

.sidebar nav a:hover {
  background: rgba(255, 255, 255, 0.05);
  color: #fff;
}

.sidebar nav a.active {
  color: var(--sidebar-active);
  background: rgba(56, 189, 248, 0.08);
  border-left-color: var(--sidebar-active);
}

.sidebar nav .nav-group {
  margin-top: 0.75rem;
  padding: 0.35rem 1.25rem 0.2rem;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #64748b;
  font-weight: 700;
}

.sidebar nav a.nav-child {
  padding-left: 1.75rem;
  font-size: 0.82rem;
}

.main {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
}

.topbar {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1.5rem;
  background: var(--content-bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.menu-toggle {
  display: none;
  background: var(--brand);
  color: #fff;
  border: 0;
  border-radius: 6px;
  padding: 0.4rem 0.7rem;
  cursor: pointer;
  font-size: 0.85rem;
}

.topbar-title {
  font-size: 0.9rem;
  color: var(--muted);
}

.content-wrap {
  padding: 1.5rem;
  max-width: 960px;
  width: 100%;
  margin: 0 auto;
}

.article {
  background: var(--content-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 2rem 2.25rem;
  box-shadow: 0 1px 2px rgba(15, 23, 42, 0.04);
}

.article h1 {
  margin-top: 0;
  color: var(--brand-dark);
  font-size: 1.85rem;
  line-height: 1.25;
  border-bottom: 2px solid var(--brand-soft);
  padding-bottom: 0.6rem;
}

.article h2 {
  margin-top: 2rem;
  color: var(--brand-dark);
  font-size: 1.3rem;
  border-left: 4px solid var(--brand);
  padding-left: 0.65rem;
}

.article h3 {
  margin-top: 1.5rem;
  color: #0f766e;
  font-size: 1.05rem;
}

.article p,
.article li {
  color: #334155;
}

.article ul,
.article ol {
  padding-left: 1.35rem;
}

.article a {
  color: var(--brand-dark);
}

.article table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.9rem;
}

.article th,
.article td {
  border: 1px solid var(--border);
  padding: 0.55rem 0.7rem;
  text-align: left;
  vertical-align: top;
}

.article th {
  background: var(--brand);
  color: #fff;
  font-weight: 600;
}

.article tr:nth-child(even) td {
  background: #f8fafc;
}

.article code {
  background: #f1f5f9;
  color: #0f172a;
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
  font-size: 0.88em;
}

.article pre {
  background: #f8fafc;
  color: #0f172a;
  padding: 1rem 1.25rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  overflow-x: auto;
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.92rem;
  line-height: 1.55;
}

.article pre code {
  background: transparent;
  color: inherit;
  padding: 0;
  font-size: inherit;
}

.article blockquote {
  margin: 1rem 0;
  padding: 0.75rem 1rem;
  background: var(--info-bg);
  border-left: 4px solid var(--info-border);
  color: #1e3a8a;
}

.article .figure-placeholder {
  margin: 1.25rem 0;
  padding: 2rem 1rem;
  text-align: center;
  background: var(--brand-soft);
  border: 1px dashed var(--brand);
  border-radius: 8px;
  color: var(--brand-dark);
  font-size: 0.9rem;
}

.article .callout-warn {
  background: var(--warn-bg);
  border-left: 4px solid var(--warn-border);
  padding: 0.75rem 1rem;
  margin: 1rem 0;
  border-radius: 0 6px 6px 0;
}

.page-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

.page-nav a {
  display: inline-block;
  padding: 0.65rem 1rem;
  background: var(--content-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  text-decoration: none;
  color: var(--brand-dark);
  font-size: 0.9rem;
  max-width: 48%;
}

.page-nav a:hover {
  border-color: var(--brand);
  background: var(--brand-soft);
}

.page-nav .next {
  margin-left: auto;
  text-align: right;
}

.home-hero {
  background: linear-gradient(135deg, #0d8a9a 0%, #0a6b77 55%, #1e293b 100%);
  color: #fff;
  border-radius: 10px;
  padding: 2.5rem 2rem;
  margin-bottom: 1.5rem;
}

.home-hero h1 {
  margin: 0 0 0.5rem;
  border: 0;
  color: #fff;
  padding: 0;
}

.home-hero p {
  margin: 0;
  opacity: 0.92;
  max-width: 36rem;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1rem;
}

.card-grid a {
  display: block;
  background: var(--content-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem 1.1rem;
  text-decoration: none;
  color: var(--text);
}

.card-grid a:hover {
  border-color: var(--brand);
  box-shadow: 0 4px 12px rgba(13, 138, 154, 0.12);
}

.card-grid strong {
  display: block;
  color: var(--brand-dark);
  margin-bottom: 0.25rem;
}

.card-grid span {
  font-size: 0.85rem;
  color: var(--muted);
}

.sidebar-overlay {
  display: none;
}

@media (max-width: 900px) {
  .menu-toggle {
    display: inline-block;
  }

  .sidebar {
    position: fixed;
    left: 0;
    transform: translateX(-105%);
    transition: transform 0.2s ease;
    box-shadow: 4px 0 24px rgba(0, 0, 0, 0.25);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .sidebar-overlay.visible {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.45);
    z-index: 15;
  }

  .content-wrap {
    padding: 1rem;
  }

  .article {
    padding: 1.25rem;
  }
}

@media print {
  .sidebar,
  .topbar,
  .page-nav,
  .menu-toggle {
    display: none !important;
  }

  .content-wrap {
    max-width: none;
    padding: 0;
  }

  .article {
    border: 0;
    box-shadow: none;
    padding: 0;
  }
}