/* ===== CSS Variables — Dark Teal Theme ===== */
:root {
  --color-primary: #2dd4bf;
  --color-primary-dim: #14b8a6;
  --color-primary-dark: #0d9488;
  --color-primary-glow: rgba(45, 212, 191, 0.12);
  --color-primary-glow-strong: rgba(45, 212, 191, 0.25);

  --bg-body: #0f1419;
  --bg-sidebar: #141b22;
  --bg-content: #0f1419;
  --bg-card: #1a2332;
  --bg-code: #1a2332;
  --bg-hover: #1e2a3a;
  --bg-active: rgba(45, 212, 191, 0.08);

  --border: #1e2d3d;
  --border-light: #2a3a4d;

  --text: #e2e8f0;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --heading: #f1f5f9;

  --success: #34d399;
  --warning: #fbbf24;
  --danger: #f87171;
  --info: #38bdf8;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Cascadia Code", "JetBrains Mono", Consolas, monospace;

  --sidebar-width: 260px;
  --toc-width: 200px;
  --content-max: 780px;
  --header-height: 52px;
  --radius: 6px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 1.25rem);
}

body {
  font-family: var(--font);
  background: var(--bg-body);
  color: var(--text);
  line-height: 1.7;
  font-size: 15px;
  min-height: 100vh;
  overflow-x: hidden;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-primary-dim); text-decoration: underline; }

/* ===== Top Header ===== */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--header-height);
  background: var(--bg-sidebar);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 1.2rem;
}
.site-title {
  font-size: 1rem; font-weight: 700; color: var(--color-primary);
  display: flex; align-items: center; gap: 0.5rem;
}
.site-title:hover { text-decoration: none; }
.site-title .logo { font-size: 1.3rem; }
.header-right { display: flex; align-items: center; gap: 1rem; }
.header-search-wrap {
  position: relative;
}
.header-search {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 0.35rem 0.7rem;
  color: var(--text-secondary); font-size: 0.82rem; width: 200px;
  outline: none; transition: border-color 0.2s;
}
.header-search:focus { border-color: var(--color-primary); }
.header-search::placeholder { color: var(--text-muted); }
.search-results[hidden] { display: none !important; }
.search-results {
  position: absolute;
  top: calc(100% + 0.45rem);
  right: 0;
  width: min(32rem, calc(100vw - 2.4rem));
  max-height: min(28rem, calc(100vh - var(--header-height) - 2rem));
  overflow-y: auto;
  background: rgba(20, 27, 34, 0.98);
  border: 1px solid var(--border-light);
  border-radius: 12px;
  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.35);
  backdrop-filter: blur(14px);
  z-index: 120;
  padding: 0.45rem;
}
.search-state {
  padding: 0.85rem 0.9rem;
  color: var(--text-secondary);
  font-size: 0.84rem;
}
.search-state-error {
  color: var(--danger);
}
.search-result-item {
  display: flex;
  flex-direction: column;
  gap: 0.16rem;
  padding: 0.7rem 0.85rem;
  border-radius: 10px;
  border: 1px solid transparent;
  color: inherit;
  text-decoration: none;
  transition: background 0.15s ease, border-color 0.15s ease;
}
.search-result-item + .search-result-item {
  margin-top: 0.12rem;
}
.search-result-item:hover,
.search-result-item.active {
  background: rgba(45, 212, 191, 0.08);
  border-color: rgba(45, 212, 191, 0.24);
  text-decoration: none;
}
.search-result-title {
  color: var(--heading);
  font-size: 0.9rem;
  font-weight: 700;
  line-height: 1.35;
}
.search-result-meta {
  color: var(--color-primary);
  font-size: 0.74rem;
  font-weight: 600;
}
.search-result-snippet {
  color: var(--text-secondary);
  font-size: 0.78rem;
  line-height: 1.5;
}
.header-link {
  font-size: 0.82rem; color: var(--text-secondary);
  display: flex; align-items: center; gap: 0.3rem;
  transition: color 0.2s;
}
.header-link:hover { color: var(--color-primary); text-decoration: none; }
.lang-switch {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 3.2rem;
  height: 2rem;
  padding: 0 0.75rem;
  border: 1px solid var(--border-light);
  border-radius: 999px;
  background: var(--bg-card);
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 700;
  line-height: 1;
  transition: all 0.15s ease;
}
.lang-switch:hover {
  color: var(--color-primary);
  border-color: var(--color-primary-dark);
  text-decoration: none;
}
.mobile-menu-btn {
  display: none; background: none; border: none;
  color: var(--text); font-size: 1.3rem; cursor: pointer;
}

/* ===== Layout: Sidebar + Content + TOC ===== */
.layout {
  display: flex;
  margin-top: var(--header-height);
  min-height: calc(100vh - var(--header-height));
}

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width); flex-shrink: 0;
  position: sticky; top: var(--header-height);
  height: calc(100vh - var(--header-height));
  overflow-y: auto; background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  padding: 1rem 0;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

.nav-group { border-bottom: 1px solid rgba(30, 45, 61, 0.35); }
.nav-group:last-child { border-bottom: none; }
.nav-category {
  list-style: none;
  padding: 0.65rem 1.2rem 0.45rem;
  font-size: 0.9rem; font-weight: 700;
  text-transform: none; letter-spacing: 0;
  color: var(--text-muted);
  cursor: pointer;
  display: flex; align-items: center; justify-content: space-between;
  user-select: none;
}
.nav-category-link {
  color: inherit;
  text-decoration: none;
  flex: 1;
  min-width: 0;
}
.nav-category-link:hover {
  color: var(--text);
  text-decoration: none;
}
.nav-category::-webkit-details-marker { display: none; }
.nav-category::after {
  content: "▾";
  font-size: 0.75rem;
  color: var(--text-muted);
  transition: transform 0.15s ease;
}
.nav-group:not([open]) .nav-category::after { transform: rotate(-90deg); }
.nav-group-items { padding-bottom: 0.35rem; }
.nav-category.active,
.nav-group[open] .nav-category {
  color: var(--text-secondary);
}
.nav-category-link.active {
  color: var(--color-primary);
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 0.2rem;
  text-decoration-thickness: 1.5px;
}
.nav-item {
  display: block; padding: 0.35rem 1.2rem 0.35rem 1.5rem;
  font-size: 0.88rem; color: var(--text-secondary);
  border-left: 3px solid transparent;
  transition: all 0.15s;
}
.nav-item-top {
  padding-top: 0.55rem;
  padding-bottom: 0.55rem;
  font-weight: 500;
}
.nav-item:hover {
  background: var(--bg-hover); color: var(--text);
  text-decoration: none; border-left-color: var(--border-light);
}
.nav-item.active {
  color: var(--color-primary); background: var(--bg-active);
  border-left-color: var(--color-primary); font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 0.2rem;
  text-decoration-thickness: 1.5px;
}
.nav-item-child {
  display: block; padding: 0.25rem 1.2rem 0.25rem 2.4rem;
  font-size: 0.82rem; color: var(--text-muted);
  transition: all 0.15s;
}
.nav-children { padding-bottom: 0.2rem; }
.nav-item-child:hover {
  color: var(--text-secondary); text-decoration: none;
}
.nav-item-child.active {
  color: var(--color-primary);
  background: rgba(45, 212, 191, 0.04);
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 0.2rem;
  text-decoration-thickness: 1.5px;
}

/* ===== TOC ===== */
.toc {
  font-size: 0.95rem;
}
.toc-title {
  font-size: 0.95rem;
  font-weight: 700;
}
.toc a {
  font-size: 0.9rem;
}
.toc .toc-h4 {
  font-size: 0.86rem;
}

/* ===== Main Content ===== */
.main-wrap {
  flex: 1; min-width: 0;
  display: flex; justify-content: center;
}
.main-content {
  width: 100%; max-width: var(--content-max);
  padding: 2rem 2.5rem 4rem;
}

/* Page header */
.page-header { margin-bottom: 2rem; }
.page-title {
  font-size: 1.8rem; font-weight: 700; color: var(--heading);
  margin-bottom: 0.3rem; line-height: 1.3;
}
.page-desc {
  font-size: 0.95rem; color: var(--text-secondary); line-height: 1.6;
}
.page-breadcrumb {
  font-size: 0.78rem; color: var(--text-muted); margin-bottom: 0.6rem;
}
.page-breadcrumb a { color: var(--text-muted); }
.page-breadcrumb a:hover { color: var(--color-primary); }

/* ===== Typography ===== */
h2 {
  font-size: 1.3rem; font-weight: 600; color: var(--heading);
  margin: 2.5rem 0 0.8rem; padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--border);
}
h3 {
  font-size: 1.1rem; font-weight: 600; color: var(--heading);
  margin: 1.8rem 0 0.6rem;
}
h4 {
  font-size: 0.95rem; font-weight: 600; color: var(--text);
  margin: 1.2rem 0 0.4rem;
}

.main-content h2,
.main-content h3,
.main-content h4 {
  scroll-margin-top: calc(var(--header-height) + 1.25rem);
}

p { margin: 0.6rem 0; color: var(--text-secondary); }

ul, ol { padding-left: 1.4rem; margin: 0.5rem 0; }
li { margin: 0.3rem 0; color: var(--text-secondary); }
li strong { color: var(--text); }

/* ===== Inline Code & Code Blocks ===== */
code {
  font-family: var(--font-mono);
  background: var(--bg-code); padding: 0.15rem 0.4rem;
  border-radius: 3px; font-size: 0.85em;
  color: var(--color-primary);
}

.code-block-wrap {
  position: relative;
  margin: 0.8rem 0;
}

pre {
  background: var(--bg-code); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 2.5rem 1.2rem 1rem;
  overflow-x: auto; margin: 0;
}
pre code {
  background: none; padding: 0; font-size: 0.84rem;
  color: var(--text); line-height: 1.6;
}
.code-copy-btn {
  position: absolute;
  top: 0.7rem;
  right: 0.8rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 3.6rem;
  padding: 0.28rem 0.7rem;
  border: 1px solid rgba(45, 212, 191, 0.28);
  border-radius: 999px;
  background: rgba(17, 24, 39, 0.88);
  color: var(--color-primary);
  font-size: 0.76rem;
  font-weight: 600;
  line-height: 1;
  cursor: pointer;
  transition: all 0.15s ease;
  z-index: 2;
}
.code-copy-btn:hover {
  background: rgba(45, 212, 191, 0.12);
  text-decoration: none;
  border-color: rgba(45, 212, 191, 0.5);
}
.code-copy-btn.copied {
  color: #0f1419;
  background: var(--color-primary);
  border-color: var(--color-primary);
}

/* ===== Tables ===== */
table {
  width: 100%; border-collapse: collapse; margin: 0.8rem 0;
  font-size: 0.88rem;
}
th {
  text-align: left; padding: 0.6rem 0.8rem;
  background: var(--bg-card); color: var(--text);
  font-weight: 600; border-bottom: 2px solid var(--border-light);
}
td {
  padding: 0.5rem 0.8rem; border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}
tr:hover td { background: var(--bg-hover); }

.home-overview-table th:first-child,
.home-overview-table td:first-child {
  width: 11rem;
}

/* ===== Images ===== */
.main-content img {
  display: block;
  width: auto;
  max-width: min(100%, 760px);
  max-height: 70vh;
  margin: 0.9rem auto;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

/* ===== Callouts / Admonitions ===== */
.callout {
  border-radius: var(--radius); padding: 0.8rem 1rem;
  margin: 0.8rem 0; border-left: 4px solid;
  font-size: 0.88rem;
}
.callout-title { font-weight: 600; margin-bottom: 0.2rem; }
.callout-info    { background: rgba(56, 189, 248, 0.08); border-left-color: var(--info); }
.callout-info .callout-title { color: var(--info); }
.callout-warning { background: rgba(251, 191, 36, 0.08); border-left-color: var(--warning); }
.callout-warning .callout-title { color: var(--warning); }
.callout-success { background: rgba(52, 211, 153, 0.08); border-left-color: var(--success); }
.callout-success .callout-title { color: var(--success); }
.callout-danger  { background: rgba(248, 113, 113, 0.08); border-left-color: var(--danger); }
.callout-danger .callout-title { color: var(--danger); }

/* ===== Buttons ===== */
.btn {
  display: inline-flex; align-items: center; gap: 0.4rem;
  padding: 0.5rem 1.1rem; border-radius: var(--radius);
  font-size: 0.85rem; font-weight: 500; cursor: pointer;
  border: none; transition: all 0.2s;
}
.btn-primary { background: var(--color-primary-dark); color: #0f1419; }
.btn-primary:hover { background: var(--color-primary); text-decoration: none; color: #0f1419; }
.btn-outline {
  background: transparent; color: var(--color-primary);
  border: 1px solid var(--color-primary-dark);
}
.btn-outline:hover { background: var(--bg-active); text-decoration: none; }
.btn-sm { padding: 0.3rem 0.7rem; font-size: 0.78rem; }

/* ===== Badges / Tags ===== */
.badge {
  display: inline-block; padding: 0.15rem 0.5rem;
  border-radius: 3px; font-size: 0.72rem; font-weight: 600;
}
.badge-teal   { background: rgba(45, 212, 191, 0.15); color: var(--color-primary); }
.badge-blue   { background: rgba(56, 189, 248, 0.15); color: var(--info); }
.badge-yellow { background: rgba(251, 191, 36, 0.15); color: var(--warning); }
.badge-green  { background: rgba(52, 211, 153, 0.15); color: var(--success); }
.badge-red    { background: rgba(248, 113, 113, 0.15); color: var(--danger); }

/* ===== Cards ===== */
.card-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem; margin: 1rem 0;
}
.card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.2rem;
  transition: all 0.2s;
}
.card:hover {
  border-color: var(--color-primary-dark);
  box-shadow: 0 0 0 1px var(--color-primary-glow);
}
.card h3 { font-size: 0.95rem; margin: 0 0 0.3rem; }
.card p { font-size: 0.82rem; color: var(--text-muted); margin: 0; }

/* ===== TOC (Right Sidebar) ===== */
.toc {
  width: var(--toc-width); flex-shrink: 0;
  position: sticky; top: calc(var(--header-height) + 2rem);
  height: fit-content; max-height: calc(100vh - var(--header-height) - 4rem);
  overflow-y: auto; padding: 0 1rem;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}
.toc-title {
  font-size: 0.7rem; font-weight: 700;
  text-transform: uppercase; letter-spacing: 0.08em;
  color: var(--text-muted); margin-bottom: 0.5rem;
}
.toc a {
  display: block; padding: 0.2rem 0; font-size: 0.78rem;
  color: var(--text-muted); line-height: 1.5;
  border-left: 2px solid transparent; padding-left: 0.6rem;
  transition: all 0.15s;
}
.toc a:hover { color: var(--text-secondary); text-decoration: none; }
.toc a.active {
  color: var(--color-primary); border-left-color: var(--color-primary);
}
.toc-h4 { padding-left: 1.2rem; }

/* ===== Footer ===== */
.site-footer {
  margin-top: 3rem; padding: 1.5rem 0;
  border-top: 1px solid var(--border);
  font-size: 0.78rem; color: var(--text-muted);
  display: flex; justify-content: space-between;
}
.site-footer a { color: var(--text-muted); }
.site-footer a:hover { color: var(--color-primary); }

/* ===== Back to top ===== */
.back-to-top {
  position: fixed; bottom: 1.5rem; right: 1.5rem;
  width: 36px; height: 36px; border-radius: 50%;
  background: var(--bg-card); border: 1px solid var(--border);
  color: var(--text-secondary); font-size: 1rem;
  display: none; align-items: center; justify-content: center;
  cursor: pointer; transition: all 0.2s; z-index: 50;
}
.back-to-top:hover { border-color: var(--color-primary); color: var(--color-primary); }
.back-to-top.visible { display: flex; }

/* ===== Responsive ===== */
@media (max-width: 1100px) {
  .toc { display: none; }
}
@media (max-width: 768px) {
  .sidebar {
    position: fixed; top: var(--header-height); left: 0;
    transform: translateX(-100%);
    z-index: 90; transition: transform 0.25s ease;
    box-shadow: none;
  }
  .sidebar.open {
    transform: translateX(0);
    box-shadow: 4px 0 20px rgba(0,0,0,0.4);
  }
  .mobile-menu-btn { display: block; }
  .main-content { padding: 1.5rem 1rem 3rem; }
  .page-title { font-size: 1.4rem; }
  .header-search { width: 140px; }
  .search-results {
    width: min(24rem, calc(100vw - 1rem));
    right: -4.2rem;
  }
  .site-footer { flex-direction: column; gap: 0.3rem; }
}