:root {
  --bg: #ffffff;
  --bg-soft: #f6f8fb;
  --bg-code: #f3f5f9;
  --text: #1b2230;
  --text-soft: #4d5869;
  --text-faint: #7a8597;
  --border: #e3e7ee;
  --accent: #1673e6;
  --accent-soft: rgba(22, 115, 230, 0.09);
  --accent-grad: linear-gradient(135deg, #22d3ee, #2f8cff 60%, #7c3aed);

  --hl-keyword: #a626a4;
  --hl-string: #2f7d32;
  --hl-number: #b45309;
  --hl-comment: #8a94a6;
  --hl-title: #1d5fd1;
  --hl-type: #0e7490;
  --hl-meta: #b45309;

  --topbar-h: 56px;
  --sidebar-w: 260px;
  --toc-w: 220px;
  --content-max: 780px;
  --radius: 8px;
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, 'JetBrains Mono', Menlo, Consolas, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    --bg: #0b0f17;
    --bg-soft: #0f1520;
    --bg-code: #121a27;
    --text: #e4e8ef;
    --text-soft: #a9b3c3;
    --text-faint: #6f7b8f;
    --border: #1f2836;
    --accent: #4fb3ff;
    --accent-soft: rgba(79, 179, 255, 0.1);
    --hl-keyword: #c792ea;
    --hl-string: #a5d6a7;
    --hl-number: #f6b26b;
    --hl-comment: #6b778c;
    --hl-title: #82aaff;
    --hl-type: #5fd4e8;
    --hl-meta: #f6b26b;
    color-scheme: dark;
  }
}
:root[data-theme='dark'] {
  --bg: #0b0f17;
  --bg-soft: #0f1520;
  --bg-code: #121a27;
  --text: #e4e8ef;
  --text-soft: #a9b3c3;
  --text-faint: #6f7b8f;
  --border: #1f2836;
  --accent: #4fb3ff;
  --accent-soft: rgba(79, 179, 255, 0.1);
  --hl-keyword: #c792ea;
  --hl-string: #a5d6a7;
  --hl-number: #f6b26b;
  --hl-comment: #6b778c;
  --hl-title: #82aaff;
  --hl-type: #5fd4e8;
  --hl-meta: #f6b26b;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-padding-top: calc(var(--topbar-h) + 16px); -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.65 var(--font);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }

.skip { position: absolute; left: -999px; top: 8px; z-index: 100; background: var(--bg); padding: 8px 12px; border-radius: var(--radius); }
.skip:focus { left: 8px; }

/* ---- top bar ---- */
.topbar {
  position: sticky; top: 0; z-index: 30;
  height: var(--topbar-h);
  display: flex; align-items: center; gap: 16px;
  padding: 0 16px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); font-weight: 600; font-size: 17px; white-space: nowrap; }
.brand:hover { text-decoration: none; }
.brand b { font-weight: 600; background: var(--accent-grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.menu-toggle { display: none; padding: 6px; margin-left: -6px; border-radius: 6px; }

.search { position: relative; flex: 1; min-width: 0; max-width: 420px; margin-left: auto; }
.search input {
  width: 100%; height: 36px; padding: 0 36px 0 12px;
  border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--bg-soft); color: var(--text); font: inherit; font-size: 14px;
}
.search input:focus { outline: 2px solid var(--accent); outline-offset: -1px; }
.search kbd {
  position: absolute; right: 8px; top: 50%; transform: translateY(-50%);
  font: 12px var(--mono); color: var(--text-faint);
  border: 1px solid var(--border); border-radius: 4px; padding: 0 5px;
}
.search input:focus + kbd { display: none; }
#search-results {
  position: absolute; top: 42px; left: 0; right: 0;
  margin: 0; padding: 6px; list-style: none;
  max-height: 60vh; overflow-y: auto;
  background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.18);
}
#search-results a { display: block; padding: 8px 10px; border-radius: 6px; color: var(--text); font-size: 14px; line-height: 1.35; }
#search-results a small { display: block; color: var(--text-faint); font-size: 12px; }
#search-results a:hover, #search-results a.active { background: var(--accent-soft); text-decoration: none; }
#search-results .empty { padding: 8px 10px; color: var(--text-faint); font-size: 14px; }

.topbar-links { display: flex; align-items: center; gap: 4px; }
.topbar-links a, .theme-toggle { display: grid; place-items: center; width: 36px; height: 36px; border-radius: 6px; color: var(--text-soft); }
.topbar-links a:hover, .theme-toggle:hover, .menu-toggle:hover { background: var(--bg-soft); color: var(--text); }
.theme-toggle .moon { display: none; }
:root[data-theme='dark'] .theme-toggle .sun { display: none; }
:root[data-theme='dark'] .theme-toggle .moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) .theme-toggle .sun { display: none; }
  :root:not([data-theme='light']) .theme-toggle .moon { display: block; }
}

/* ---- three-column layout ---- */
.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr) var(--toc-w);
  max-width: 1440px; margin: 0 auto;
}
.sidebar {
  position: sticky; top: var(--topbar-h);
  height: calc(100vh - var(--topbar-h));
  overflow-y: auto;
  padding: 24px 16px 40px;
  border-right: 1px solid var(--border);
}
.nav-section + .nav-section { margin-top: 22px; }
.nav-title { margin: 0 0 6px 10px; font-size: 12px; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase; color: var(--text-faint); }
.sidebar ul { list-style: none; margin: 0; padding: 0; }
.sidebar a {
  display: block; padding: 5px 10px; border-radius: 6px;
  color: var(--text-soft); font-size: 14.5px;
}
.sidebar a:hover { background: var(--bg-soft); color: var(--text); text-decoration: none; }
.sidebar a[aria-current='page'] { background: var(--accent-soft); color: var(--accent); font-weight: 600; }

.content { min-width: 0; padding: 32px 48px 48px; }
.content > * { max-width: var(--content-max); margin-left: auto; margin-right: auto; }
.breadcrumb { margin-top: 0; margin-bottom: 4px; font-size: 13px; font-weight: 600; color: var(--accent); }

.toc {
  position: sticky; top: var(--topbar-h);
  height: calc(100vh - var(--topbar-h));
  overflow-y: auto; padding: 32px 16px 40px 8px;
  font-size: 13px;
}
.toc-title { margin: 0 0 8px; font-weight: 600; color: var(--text); }
.toc ul { list-style: none; margin: 0; padding: 0; border-left: 1px solid var(--border); }
.toc a { display: block; padding: 3px 0 3px 12px; margin-left: -1px; border-left: 1px solid transparent; color: var(--text-faint); line-height: 1.4; }
.toc .d3 a { padding-left: 24px; }
.toc a:hover { color: var(--text); text-decoration: none; }
.toc a.active { color: var(--accent); border-left-color: var(--accent); }

/* ---- prose ---- */
.prose h1 { font-size: 2.2rem; line-height: 1.2; letter-spacing: -0.02em; margin: 0 0 20px; }
.prose h2 { font-size: 1.5rem; line-height: 1.3; letter-spacing: -0.01em; margin: 48px 0 14px; padding-top: 20px; border-top: 1px solid var(--border); }
.prose h3 { font-size: 1.18rem; margin: 32px 0 10px; }
.prose h4 { font-size: 1rem; margin: 24px 0 8px; }
.prose h2, .prose h3, .prose h4 { position: relative; }
.prose .anchor { position: absolute; left: -1.1em; width: 1em; color: var(--text-faint); opacity: 0; font-weight: 400; }
.prose h2:hover .anchor, .prose h3:hover .anchor, .prose h4:hover .anchor, .prose .anchor:focus { opacity: 1; text-decoration: none; }
.prose p, .prose ul, .prose ol { margin: 0 0 16px; }
.prose li { margin: 4px 0; }
.prose li > ul, .prose li > ol { margin: 4px 0; }
.prose img { max-width: 100%; height: auto; border-radius: 12px; }
.prose blockquote {
  margin: 0 0 16px; padding: 10px 16px;
  border-left: 3px solid var(--accent); background: var(--accent-soft);
  border-radius: 0 var(--radius) var(--radius) 0; color: var(--text-soft);
}
.prose blockquote p:last-child { margin-bottom: 0; }
.prose hr { border: 0; border-top: 1px solid var(--border); margin: 32px 0; }

.prose code { font-family: var(--mono); font-size: 0.875em; }
.prose :not(pre) > code { background: var(--bg-code); border: 1px solid var(--border); border-radius: 5px; padding: 0.1em 0.35em; overflow-wrap: anywhere; }
.code-block { position: relative; margin: 0 0 20px; }
.code-block pre {
  margin: 0; padding: 16px 18px; overflow-x: auto;
  background: var(--bg-code); border: 1px solid var(--border); border-radius: var(--radius);
  font-size: 13.5px; line-height: 1.6; tab-size: 4;
}
.code-lang { position: absolute; top: 6px; right: 12px; font: 11px var(--mono); color: var(--text-faint); text-transform: lowercase; pointer-events: none; transition: opacity 0.15s; }
.copy {
  position: absolute; top: 6px; right: 6px;
  padding: 3px 8px; border: 1px solid var(--border); border-radius: 5px;
  background: var(--bg); color: var(--text-soft); font-size: 12px;
  opacity: 0; transition: opacity 0.15s;
}
.code-block:hover .copy, .copy:focus { opacity: 1; }
.code-block:hover .code-lang { opacity: 0; }

.table-wrap { overflow-x: auto; margin: 0 0 20px; border: 1px solid var(--border); border-radius: var(--radius); }
.prose table { border-collapse: collapse; width: 100%; font-size: 14.5px; }
.prose th, .prose td { padding: 8px 12px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
.prose th { background: var(--bg-soft); font-weight: 600; }
.prose tr:last-child td { border-bottom: 0; }

/* highlight.js tokens */
.hljs-keyword, .hljs-selector-tag, .hljs-doctag { color: var(--hl-keyword); }
.hljs-string, .hljs-regexp, .hljs-addition { color: var(--hl-string); }
.hljs-number, .hljs-literal, .hljs-symbol, .hljs-bullet { color: var(--hl-number); }
.hljs-comment, .hljs-quote { color: var(--hl-comment); font-style: italic; }
.hljs-title, .hljs-section, .hljs-function .hljs-title { color: var(--hl-title); }
.hljs-type, .hljs-built_in, .hljs-class .hljs-title, .hljs-title.class_ { color: var(--hl-type); }
.hljs-meta, .hljs-attr, .hljs-attribute, .hljs-variable, .hljs-template-variable { color: var(--hl-meta); }
.hljs-deletion { color: #dc2626; }

/* ---- page footer ---- */
.edit { margin-top: 40px; font-size: 14px; }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 24px; }
.pager a { display: block; padding: 14px 16px; border: 1px solid var(--border); border-radius: var(--radius); color: var(--text); font-weight: 600; }
.pager a:hover { border-color: var(--accent); text-decoration: none; }
.pager span { display: block; font-size: 12px; font-weight: 400; color: var(--text-faint); }
.pager-next { text-align: right; grid-column: 2; }
.footer { margin-top: 48px; padding-top: 20px; border-top: 1px solid var(--border); font-size: 13px; color: var(--text-faint); }

.scrim { display: none; }

/* ---- responsive ---- */
@media (max-width: 1180px) {
  .layout { grid-template-columns: var(--sidebar-w) minmax(0, 1fr); }
  .toc { display: none; }
}
@media (max-width: 860px) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .menu-toggle { display: grid; place-items: center; }
  .sidebar {
    position: fixed; z-index: 25; left: 0; top: var(--topbar-h);
    width: min(300px, 85vw); background: var(--bg);
    transform: translateX(-100%); transition: transform 0.2s ease;
  }
  body.nav-open .sidebar { transform: none; box-shadow: 0 0 40px rgba(0, 0, 0, 0.25); }
  body.nav-open .scrim { display: block; position: fixed; inset: var(--topbar-h) 0 0 0; z-index: 20; background: rgba(0, 0, 0, 0.35); }
  .content { padding: 24px 16px 40px; }
  .prose h1 { font-size: 1.8rem; }
  .prose .anchor { display: none; }
  .search kbd { display: none; }
}
@media (max-width: 520px) {
  .brand span { display: none; }
  .topbar { gap: 10px; }
  .pager { grid-template-columns: 1fr; }
  .pager-next { grid-column: 1; }
}