:root {
  --bg: #ffffff;
  --bg-soft: #f6f7f9;
  --text: #1c2330;
  --muted: #5d6778;
  --border: #e3e6eb;
  --accent: #0b6bcb;
  --accent-soft: #e8f1fb;
  --code-bg: #f1f3f6;
  --topbar-h: 56px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151b;
    --bg-soft: #181c23;
    --text: #e4e7ec;
    --muted: #9aa3b2;
    --border: #2a303a;
    --accent: #5aa9f5;
    --accent-soft: #1b2a3c;
    --code-bg: #1e232c;
  }
}
* { box-sizing: border-box; }
html { scroll-padding-top: calc(var(--topbar-h) + 16px); }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.7 'Be Vietnam Pro', system-ui, -apple-system, 'Segoe UI', sans-serif;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.topbar {
  position: sticky; top: 0; z-index: 20;
  height: var(--topbar-h);
  display: flex; align-items: center; gap: 12px;
  padding: 0 20px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; color: var(--text); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.menu-btn { display: none; background: none; border: 1px solid var(--border); border-radius: 6px; color: var(--text); font-size: 18px; padding: 2px 10px; cursor: pointer; }

.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr) 240px;
  max-width: 1500px; margin: 0 auto;
}
.sidebar, .toc {
  position: sticky; top: var(--topbar-h);
  height: calc(100vh - var(--topbar-h));
  overflow-y: auto;
  padding: 20px 12px;
}
.sidebar { border-right: 1px solid var(--border); background: var(--bg); }
.sidebar ul, .toc ul { list-style: none; margin: 0; padding: 0; }
.sidebar a {
  display: flex; gap: 10px; align-items: baseline;
  padding: 7px 10px; border-radius: 6px;
  color: var(--text); font-size: 14px; line-height: 1.4;
}
.sidebar a:hover { background: var(--bg-soft); text-decoration: none; }
.sidebar a.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.sidebar .num { flex: 0 0 22px; color: var(--muted); font-variant-numeric: tabular-nums; font-size: 13px; }
.sidebar a.active .num { color: var(--accent); }

.toc { font-size: 13px; }
.toc-title { font-weight: 600; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; font-size: 12px; margin-bottom: 8px; }
.toc a { display: block; padding: 3px 0; color: var(--muted); line-height: 1.4; }
.toc a:hover { color: var(--accent); }
.toc .d3 a { padding-left: 12px; }

.content { padding: 32px 48px 64px; min-width: 0; }
.markdown { max-width: 900px; }
.markdown h1 { font-size: 2rem; line-height: 1.3; margin: 0 0 1rem; }
.markdown h2 { font-size: 1.45rem; margin: 2.2rem 0 .8rem; padding-bottom: .3rem; border-bottom: 1px solid var(--border); }
.markdown h3 { font-size: 1.15rem; margin: 1.8rem 0 .6rem; }
.markdown h4 { font-size: 1rem; margin: 1.4rem 0 .5rem; }
.markdown .anchor { float: left; margin-left: -1em; padding-right: .25em; opacity: 0; color: var(--muted); }
.markdown h1:hover .anchor, .markdown h2:hover .anchor, .markdown h3:hover .anchor, .markdown h4:hover .anchor { opacity: 1; text-decoration: none; }
.markdown blockquote {
  margin: 1rem 0; padding: .6rem 1rem;
  border-left: 4px solid var(--accent);
  background: var(--accent-soft); border-radius: 0 6px 6px 0;
}
.markdown blockquote p { margin: .2rem 0; }
.markdown code {
  font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: .86em;
  background: var(--code-bg); padding: .1em .35em; border-radius: 4px;
}
.markdown pre { background: var(--code-bg); padding: 14px 16px; border-radius: 8px; overflow-x: auto; line-height: 1.5; }
.markdown pre code { background: none; padding: 0; }
.markdown pre.mermaid { background: var(--bg-soft); border: 1px solid var(--border); text-align: center; }
.table-wrap { overflow-x: auto; margin: 1rem 0; border: 1px solid var(--border); border-radius: 8px; }
.markdown table { border-collapse: collapse; width: 100%; font-size: 14px; line-height: 1.5; }
.markdown th, .markdown td { padding: 8px 12px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
.markdown th { background: var(--bg-soft); font-weight: 600; }
.markdown tr:last-child td { border-bottom: 0; }
.markdown hr { border: 0; border-top: 1px solid var(--border); margin: 2rem 0; }
.markdown img { max-width: 100%; }

.pager {
  max-width: 900px; display: flex; justify-content: space-between; gap: 16px;
  margin-top: 48px; padding-top: 20px; border-top: 1px solid var(--border); font-size: 14px;
}
.pager a { padding: 10px 14px; border: 1px solid var(--border); border-radius: 8px; max-width: 48%; }
.pager .next { text-align: right; margin-left: auto; }
.scrim { display: none; }

@media (max-width: 1200px) {
  .layout { grid-template-columns: 260px minmax(0, 1fr); }
  .toc { display: none; }
}
@media (max-width: 860px) {
  .layout { display: block; }
  .menu-btn { display: block; }
  .topbar { padding: 0 16px; }
  .sidebar {
    position: fixed; top: var(--topbar-h); left: 0; z-index: 30;
    width: 280px; transform: translateX(-100%); transition: transform .2s;
  }
  body.nav-open .sidebar { transform: none; }
  body.nav-open .scrim { display: block; position: fixed; inset: var(--topbar-h) 0 0 0; background: rgba(0,0,0,.35); z-index: 25; }
  .content { padding: 20px 16px 48px; }
  .markdown h1 { font-size: 1.6rem; }
}