:root {
  --bg: #ffffff;
  --fg: #1b1f24;
  --muted: #5b6673;
  --border: #e3e8ee;
  --border-strong: #cdd5df;
  --code-bg: #f5f7fa;
  --accent: #2f6feb;
  --accent-soft: #eaf1fe;
  --accent-2: #f2994a;
  --link: #1a5fd0;
  --topbar-bg: #0b1f3a;
  --topbar-fg: #f2f5fa;
  --sidebar-bg: #fbfcfe;
  --sidebar-w: 280px;
  --toc-w: 220px;
  --content-max: 800px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #e6edf3;
    --muted: #9aa4b2;
    --border: #242c38;
    --border-strong: #33404f;
    --code-bg: #161b22;
    --accent: #5b9bff;
    --accent-soft: #16233c;
    --link: #79b3ff;
    --topbar-bg: #05101f;
    --sidebar-bg: #0f151d;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 4.5rem; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 15px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---- top bar ---- */
.topbar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; gap: 1rem;
  padding: 0.7rem 1.25rem;
  background: var(--topbar-bg); color: var(--topbar-fg);
}
.topbar .brand { font-weight: 700; font-size: 1.05rem; color: var(--topbar-fg); white-space: nowrap; }
.topbar .brand span { color: var(--accent-2); }
.topbar-links { display: flex; align-items: center; gap: 1.1rem; margin-left: auto; flex-wrap: wrap; }
.topbar-links a { color: var(--topbar-fg); opacity: 0.85; font-size: 0.92rem; }
.topbar-links a:hover { opacity: 1; text-decoration: none; }
.topbar-links a.cta {
  background: var(--accent); opacity: 1; padding: 0.35rem 0.75rem; border-radius: 6px; font-weight: 600;
}
.menu-toggle {
  display: none; background: none; border: 0; color: var(--topbar-fg);
  font-size: 1.25rem; cursor: pointer; padding: 0;
}

/* ---- layout ---- */
.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr) var(--toc-w);
  max-width: 1360px; margin: 0 auto;
}

/* ---- sidebar ---- */
.sidebar {
  position: sticky; top: 3.4rem; align-self: start;
  height: calc(100vh - 3.4rem); overflow-y: auto;
  padding: 1.5rem 1rem 3rem;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border);
}
.side-group { margin-bottom: 1.4rem; }
.side-group-title {
  margin: 0 0 0.4rem; padding: 0 0.5rem;
  font-size: 0.72rem; font-weight: 700; letter-spacing: 0.06em;
  text-transform: uppercase; color: var(--muted);
}
.side-group ul { list-style: none; margin: 0; padding: 0; }
.side-group li a {
  display: block; padding: 0.32rem 0.5rem; border-radius: 6px;
  color: var(--fg); font-size: 0.9rem;
}
.side-group li a:hover { background: var(--code-bg); text-decoration: none; }
.side-group li a.active {
  background: var(--accent-soft); color: var(--accent); font-weight: 600;
}

/* ---- content ---- */
.content { padding: 2.2rem 2.5rem 4rem; min-width: 0; }
.doc { max-width: var(--content-max); }
.doc h1 { font-size: 2rem; line-height: 1.2; margin: 0 0 1rem; }
.doc h2 {
  font-size: 1.4rem; margin: 2.4rem 0 0.8rem; padding-top: 0.3rem;
  border-top: 1px solid var(--border);
}
.doc h2:first-of-type { border-top: 0; }
.doc h3 { font-size: 1.1rem; margin: 1.8rem 0 0.6rem; }
.doc h2 a, .doc h3 a, .doc h1 a { color: inherit; }
.doc p, .doc li { color: var(--fg); }
.doc ul, .doc ol { padding-left: 1.35rem; }
.doc li { margin: 0.3rem 0; }
.doc code {
  background: var(--code-bg); border: 1px solid var(--border);
  border-radius: 4px; padding: 0.08em 0.35em; font-size: 0.86em;
  font-family: "SF Mono", "Fira Code", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
.doc pre {
  background: var(--code-bg); border: 1px solid var(--border);
  border-radius: 8px; padding: 1rem 1.1rem; overflow-x: auto; line-height: 1.55;
}
.doc pre code { background: none; border: 0; padding: 0; font-size: 0.85rem; }
.doc blockquote {
  margin: 1.2rem 0; padding: 0.2rem 1rem; border-left: 3px solid var(--accent);
  background: var(--accent-soft); border-radius: 0 6px 6px 0; color: var(--fg);
}
.doc blockquote p { margin: 0.6rem 0; }
.doc table {
  border-collapse: collapse; width: 100%; margin: 1.2rem 0; font-size: 0.9rem;
  display: block; overflow-x: auto;
}
.doc th, .doc td { border: 1px solid var(--border-strong); padding: 0.5rem 0.7rem; text-align: left; vertical-align: top; }
.doc th { background: var(--code-bg); }
.doc img { max-width: 100%; }
.doc hr { border: 0; border-top: 1px solid var(--border); margin: 2.4rem 0; }

/* ---- pager ---- */
.pager {
  max-width: var(--content-max);
  display: flex; justify-content: space-between; gap: 1rem;
  margin-top: 3rem; padding-top: 1.5rem; border-top: 1px solid var(--border);
}
.pager-link {
  display: flex; flex-direction: column; gap: 0.2rem;
  padding: 0.8rem 1rem; border: 1px solid var(--border-strong); border-radius: 8px;
  min-width: 45%;
}
.pager-link:hover { border-color: var(--accent); text-decoration: none; }
.pager-link.next { text-align: right; margin-left: auto; }
.pager-link span { font-size: 0.8rem; color: var(--muted); }

.doc-footer {
  max-width: var(--content-max);
  margin-top: 2.5rem; padding-top: 1.2rem; border-top: 1px solid var(--border);
  color: var(--muted); font-size: 0.85rem;
}

/* ---- toc ---- */
.toc {
  position: sticky; top: 3.4rem; align-self: start;
  height: calc(100vh - 3.4rem); overflow-y: auto;
  padding: 2.2rem 1rem 3rem 0.5rem; font-size: 0.85rem;
}
.toc-title {
  margin: 0 0 0.5rem; font-size: 0.72rem; font-weight: 700;
  letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted);
}
.toc ul { list-style: none; margin: 0; padding: 0; }
.toc li { margin: 0.15rem 0; }
.toc li.lvl-3 { padding-left: 0.8rem; }
.toc a { color: var(--muted); display: block; padding: 0.15rem 0; }
.toc a:hover { color: var(--fg); text-decoration: none; }
.toc a.active { color: var(--accent); font-weight: 600; }

/* ---- responsive ---- */
@media (max-width: 1100px) {
  .layout { grid-template-columns: var(--sidebar-w) minmax(0, 1fr); }
  .toc { display: none; }
}
@media (max-width: 820px) {
  .layout { grid-template-columns: 1fr; }
  .menu-toggle { display: block; }
  .topbar-links { display: none; }
  .sidebar {
    position: fixed; top: 3.1rem; left: 0; bottom: 0; width: min(85vw, var(--sidebar-w));
    z-index: 30; transform: translateX(-100%); transition: transform 0.2s ease;
    border-right: 1px solid var(--border-strong);
  }
  .sidebar.open { transform: translateX(0); box-shadow: 0 0 40px rgba(0,0,0,0.25); }
  .content { padding: 1.5rem 1.25rem 3rem; }
  .doc h1 { font-size: 1.6rem; }
}