:root {
  --bg: #ffffff;
  --fg: #1f2328;
  --muted: #656d76;
  --border: #d8dee4;
  --side-bg: #f6f8fa;
  --accent: #0969da;
  --accent-bg: #ddf4ff;
  --code-bg: #f6f8fa;
  --mark: #fff8c5;
  --note: #0969da; --tip: #1a7f37; --warning: #9a6700; --caution: #cf222e;
  --sidebar-w: 300px;
  --topbar-h: 52px;
}
* { box-sizing: border-box; }
html, body { margin: 0; background: var(--bg); color: var(--fg); }
body { font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Helvetica, Arial, sans-serif; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.topbar { position: fixed; top: 0; left: 0; right: 0; height: var(--topbar-h); display: flex; align-items: center; gap: 12px; padding: 0 16px; background: var(--bg); border-bottom: 1px solid var(--border); z-index: 20; }
.brand { font-weight: 600; color: var(--fg); }
.lang { margin-left: auto; display: flex; gap: 4px; }
.lang a { padding: 4px 10px; border-radius: 6px; color: var(--muted); font-size: 14px; }
.lang a.active { background: var(--accent-bg); color: var(--accent); }
.menu-btn { display: none; background: none; border: 1px solid var(--border); border-radius: 6px; font-size: 18px; padding: 2px 8px; cursor: pointer; color: var(--fg); }

.layout { display: flex; padding-top: var(--topbar-h); }
.sidebar { position: fixed; top: var(--topbar-h); bottom: 0; left: 0; width: var(--sidebar-w); overflow-y: auto; background: var(--side-bg); border-right: 1px solid var(--border); padding: 12px 0 24px; }
.content { flex: 1; margin-left: var(--sidebar-w); min-width: 0; padding-bottom: 80px; }
.markdown { max-width: 860px; margin: 0 auto; padding: 24px 32px 0; }

.search { padding: 0 12px 8px; }
.search input { width: 100%; padding: 7px 10px; border: 1px solid var(--border); border-radius: 6px; font-size: 14px; background: var(--bg); color: var(--fg); }
.search input:focus { outline: 2px solid var(--accent-bg); border-color: var(--accent); }

.nav { padding: 0 8px; font-size: 14px; }
.nav ul { list-style: none; margin: 0; padding: 0; }
.nav .group { margin-top: 6px; }
.nav .group-title { display: flex; align-items: center; width: 100%; margin: 14px 0 4px; padding: 4px 8px; background: none; border: 0; cursor: pointer; font: inherit; font-size: 12px; font-weight: 600; letter-spacing: .04em; text-transform: uppercase; color: var(--muted); text-align: left; border-radius: 6px; }
.nav .group-title:hover { background: #eaeef2; color: var(--fg); }
.nav .group-title .toggle { margin-left: auto; }
.nav .group.collapsed > ul { display: none; }
.nav .row { display: flex; align-items: center; border-radius: 6px; }
.nav .row:hover { background: #eaeef2; }
.nav .row a { flex: 1; min-width: 0; padding: 6px 8px; color: var(--fg); line-height: 1.5; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; border-radius: 6px; }
.nav .row a:hover { text-decoration: none; }
.nav .row a.active { color: var(--accent); background: var(--accent-bg); font-weight: 500; }
.nav .row:has(> a.active) { background: var(--accent-bg); }
.nav .toggle { flex: none; display: inline-flex; align-items: center; justify-content: center; width: 24px; height: 24px; margin: 0 2px; padding: 0; border: 0; border-radius: 6px; background: none; color: var(--muted); cursor: pointer; }
.nav .toggle:hover { background: #d8dee4; color: var(--fg); }
.nav .toggle svg { transition: transform .15s; transform: rotate(90deg); }
.nav .collapsed > .row > .toggle svg, .nav .group.collapsed > .group-title .toggle svg { transform: none; }
.nav li.has-children.collapsed > ul { display: none; }
.nav ul ul { margin: 2px 0 2px 14px; padding-left: 10px; border-left: 1px solid var(--border); }
.nav ul ul .row a { padding: 5px 8px; color: #424a53; }

.results { list-style: none; margin: 0; padding: 0 8px; }
.results li a { display: block; padding: 8px 10px; border-radius: 6px; color: var(--fg); font-size: 13px; }
.results li a:hover { background: #eaeef2; text-decoration: none; }
.results .r-title { font-weight: 600; }
.results .r-page { color: var(--muted); font-size: 12px; }
.results .r-snippet { color: var(--muted); margin-top: 2px; }
.results .empty { padding: 12px; color: var(--muted); font-size: 13px; }
mark.hl { background: var(--mark); color: inherit; padding: 0 1px; border-radius: 2px; }

/* markdown body */
.markdown h1 { font-size: 2em; border-bottom: 1px solid var(--border); padding-bottom: .3em; margin-top: 0; }
.markdown h2 { font-size: 1.5em; border-bottom: 1px solid var(--border); padding-bottom: .3em; margin-top: 1.6em; }
.markdown h3 { font-size: 1.25em; margin-top: 1.4em; }
.markdown h1, .markdown h2, .markdown h3, .markdown h4 { line-height: 1.3; scroll-margin-top: calc(var(--topbar-h) + 16px); }
.markdown .description { color: var(--muted); font-size: 1.05em; margin: -8px 0 24px; }
.markdown img { display: block; max-width: 100%; height: auto; margin: 16px auto; }
.markdown p:has(> img:only-child) { text-align: center; }
.markdown pre { background: var(--code-bg); padding: 12px 16px; border-radius: 6px; overflow-x: auto; font-size: 13px; }
.markdown code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .9em; background: var(--code-bg); padding: .15em .35em; border-radius: 4px; word-break: break-all; }
.markdown pre code { background: none; padding: 0; word-break: normal; }
.markdown table { border-collapse: collapse; display: block; overflow-x: auto; max-width: 100%; margin: 16px 0; font-size: 14px; }
.markdown th, .markdown td { border: 1px solid var(--border); padding: 6px 12px; vertical-align: top; }
.markdown th { background: var(--side-bg); text-align: left; }
.markdown blockquote { margin: 16px 0; padding: 0 16px; color: var(--muted); border-left: 4px solid var(--border); }
.markdown details { border: 1px solid var(--border); border-radius: 6px; padding: 8px 14px; margin: 12px 0; }
.markdown summary { cursor: pointer; font-weight: 500; }
.markdown hr { border: 0; border-top: 1px solid var(--border); margin: 24px 0; }
.markdown figcaption, .markdown .caption { color: var(--muted); font-size: .9em; text-align: center; margin-top: -8px; }

.alert { border-left-width: 4px; color: var(--fg); padding: 8px 16px; border-radius: 0 6px 6px 0; background: var(--side-bg); }
.alert .alert-title { display: block; font-weight: 600; margin-bottom: 4px; }
.alert-note { border-left-color: var(--note); } .alert-note .alert-title { color: var(--note); }
.alert-tip { border-left-color: var(--tip); } .alert-tip .alert-title { color: var(--tip); }
.alert-warning { border-left-color: var(--warning); } .alert-warning .alert-title { color: var(--warning); }
.alert-caution { border-left-color: var(--caution); } .alert-caution .alert-title { color: var(--caution); }

.markdown a.card { display: flex; align-items: center; justify-content: space-between; gap: 16px; width: 100%; max-width: 48rem; margin: 0 auto 12px; padding: 12px 20px; border-radius: 4px; color: var(--fg); font-weight: 500; box-shadow: 0 0 0 1px #e2e6ec; transition: box-shadow .15s; }
.markdown a.card:hover { text-decoration: none; box-shadow: 0 0 0 1px #c6dafd, 0 1px 3px rgba(0,0,0,.06); color: var(--accent); }
.markdown a.card svg { flex: none; width: 14px; height: 14px; color: var(--muted); }
.markdown a.card:hover svg { color: var(--accent); }

/* previous / next page cards (GitBook style) */
.pager { display: flex; gap: 12px; max-width: 860px; margin: 0 auto; padding: 48px 32px 0; }
.pager[hidden] { display: none; }
.pager-link { flex: 1; display: flex; align-items: center; gap: 12px; min-width: 0; padding: 16px; border: 1px solid var(--border); border-radius: 12px; color: var(--muted); font-size: 16px; text-wrap: pretty; transition: border-color .15s; }
.pager-link:hover { text-decoration: none; border-color: var(--accent); }
.pager-link svg { flex: none; width: 12px; height: 12px; }
.pager-prev { flex-direction: row-reverse; justify-content: flex-end; }
.pager-prev svg { transform: rotate(180deg); }
.pager-next { justify-content: flex-end; }
.pager-next .pager-text { align-items: flex-end; text-align: right; }
.pager-text { display: flex; flex-direction: column; min-width: 0; }
.pager-label { font-size: 12px; }
.pager-title { color: var(--fg); line-height: 1.4; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; transition: color .15s; }
.pager-link:hover .pager-title { color: var(--accent); }

.error { color: var(--caution); }
.backdrop { display: none; }

@media (max-width: 900px) {
  .menu-btn { display: inline-block; }
  .sidebar { transform: translateX(-100%); transition: transform .2s; z-index: 15; width: min(var(--sidebar-w), 85vw); }
  body.nav-open .sidebar { transform: none; }
  body.nav-open .backdrop { display: block; position: fixed; inset: var(--topbar-h) 0 0 0; background: rgba(0,0,0,.3); z-index: 10; }
  .content { margin-left: 0; padding-bottom: 60px; }
  .markdown { padding: 16px 16px 0; }
  .pager { flex-direction: column; padding: 32px 16px 0; }
  .pager-link { padding: 12px; font-size: 14px; }
}