/* ============================================================================
   KTH 全栈 AI 开发指引 · 手册站点样式
   ----------------------------------------------------------------------------
   只放样式，无内联 JS；无外部 CDN。暗色文档风，侧边章节目录 + 正文。
   ========================================================================== */

:root {
  --bg: #0a0e15;
  --bg-grad: radial-gradient(1100px 520px at 12% -8%, #12233d 0%, transparent 58%),
             radial-gradient(900px 480px at 100% 0%, #1a1330 0%, transparent 52%);
  --panel: #0f1621;
  --panel-2: #141d2a;
  --panel-3: #1a2534;
  --line: #1e2a3a;
  --line-2: #27384d;
  --text: #e9f0f8;
  --text-2: #a6b6c9;
  --text-3: #74879d;
  --text-4: #4c5c70;
  --brand: #3b82f6;
  --brand-2: #22d3ee;
  --accent: #a855f7;
  --ok: #34d399;
  --warn: #fbbf24;
  --danger: #f87171;
  --code-bg: #0a0f17;
  --r: 12px;
  --r-sm: 9px;
  --sidebar-w: 272px;
  --font: "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, system-ui, sans-serif;
  --mono: ui-monospace, "JetBrains Mono", "Cascadia Code", Consolas, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; font: 14px/1.75 var(--font); color: var(--text);
  background-color: var(--bg); background-image: var(--bg-grad); background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--brand-2); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { line-height: 1.4; letter-spacing: .2px; }
p { margin: 10px 0; }
ul, ol { padding-left: 22px; }
li { margin: 4px 0; }
::selection { background: rgba(59,130,246,.35); }
* { scrollbar-width: thin; scrollbar-color: var(--line-2) transparent; }
*::-webkit-scrollbar { width: 10px; height: 10px; }
*::-webkit-scrollbar-thumb { background: var(--line-2); border-radius: 999px; border: 3px solid transparent; background-clip: content-box; }

/* ---------------------------------------------------------------- 布局 */
.layout { display: grid; grid-template-columns: var(--sidebar-w) minmax(0, 1fr); min-height: 100vh; }

.sidebar {
  position: sticky; top: 0; height: 100vh; overflow: auto;
  border-right: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(15,22,33,.92), rgba(10,14,21,.92));
  padding: 16px 12px 40px;
}
.brand { display: flex; align-items: center; gap: 10px; padding: 4px 8px 14px; }
.brand .logo {
  width: 30px; height: 30px; border-radius: 9px; flex: none;
  display: inline-flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--brand), var(--brand-2)); color: #06121f; font-weight: 800;
}
.brand .t { font-weight: 700; font-size: 14px; line-height: 1.25; }
.brand .s { font-size: 11px; color: var(--text-3); }
.sidebar .group { margin: 14px 0 4px; padding: 0 10px; font-size: 10.5px; letter-spacing: 1.1px; text-transform: uppercase; color: var(--text-4); }
.sidebar a.item { display: block; padding: 7px 10px; margin: 1px 0; border-radius: 8px; color: var(--text-2); font-size: 13px; }
.sidebar a.item:hover { background: var(--panel-2); color: var(--text); text-decoration: none; }
.sidebar a.item.on { background: rgba(59,130,246,.14); color: #cfe2ff; font-weight: 600; }
.sidebar .foot { margin-top: 18px; padding: 10px 10px 0; border-top: 1px solid var(--line); font-size: 11.5px; color: var(--text-4); }

.main { min-width: 0; }
.doc-top {
  position: sticky; top: 0; z-index: 20; display: flex; align-items: center; gap: 12px;
  padding: 10px 26px; border-bottom: 1px solid var(--line);
  background: rgba(10,14,21,.82); backdrop-filter: blur(10px);
}
.doc-top .crumbs { font-size: 12px; color: var(--text-3); }
.doc-top .crumbs b { color: var(--text); font-weight: 600; }
.doc-top .spacer { flex: 1; }
.doc-top .chip { font-size: 11px; padding: 3px 9px; border-radius: 999px; border: 1px solid var(--line-2); color: var(--text-3); }
.menu-btn { display: none; }

.doc { max-width: 920px; padding: 34px 26px 90px; margin: 0 auto; }
.doc h1 { font-size: 27px; margin: 0 0 6px; }
.doc .lead { color: var(--text-2); font-size: 14.5px; margin: 0 0 22px; }
.doc h2 { font-size: 20px; margin: 40px 0 12px; padding-top: 8px; border-top: 1px solid var(--line); }
.doc h3 { font-size: 16px; margin: 26px 0 8px; }
.doc h4 { font-size: 14px; margin: 18px 0 6px; color: var(--text-2); }
.doc h2 .anchor, .doc h3 .anchor { color: var(--text-4); font-weight: 400; font-size: .72em; margin-left: 8px; opacity: 0; }
.doc h2:hover .anchor, .doc h3:hover .anchor { opacity: 1; }

/* ---------------------------------------------------------------- 组件 */
.card { background: linear-gradient(180deg, rgba(20,29,42,.72), rgba(15,22,33,.72)); border: 1px solid var(--line); border-radius: var(--r); padding: 16px 18px; margin: 14px 0; }
.card .ct { font-weight: 600; margin-bottom: 6px; }

.steps { counter-reset: st; list-style: none; padding: 0; margin: 14px 0; }
.steps > li { position: relative; padding: 0 0 16px 40px; }
.steps > li::before {
  counter-increment: st; content: counter(st);
  position: absolute; left: 0; top: 0; width: 26px; height: 26px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center; font-size: 12.5px; font-weight: 700;
  background: rgba(59,130,246,.15); color: #cfe2ff; border: 1px solid rgba(59,130,246,.45);
}
.steps > li::after { content: ""; position: absolute; left: 13px; top: 30px; bottom: 2px; width: 1px; background: var(--line-2); }
.steps > li:last-child::after { display: none; }
.steps .st-t { font-weight: 600; }

.callout { border: 1px solid var(--line-2); border-left-width: 3px; border-radius: var(--r-sm); padding: 12px 14px; margin: 14px 0; background: var(--panel); }
.callout .k { font-weight: 700; font-size: 12.5px; letter-spacing: .3px; }
.callout p:first-child { margin-top: 0; } .callout p:last-child { margin-bottom: 0; }
.callout.tip { border-left-color: var(--ok); } .callout.tip .k { color: var(--ok); }
.callout.info { border-left-color: var(--brand); } .callout.info .k { color: #93c5fd; }
.callout.warn { border-left-color: var(--warn); } .callout.warn .k { color: var(--warn); }
.callout.danger { border-left-color: var(--danger); } .callout.danger .k { color: var(--danger); }

/* 代码块 */
.codeblock { margin: 12px 0; border: 1px solid var(--line); border-radius: var(--r-sm); overflow: hidden; background: var(--code-bg); }
.codeblock .cb-hd { display: flex; align-items: center; gap: 8px; padding: 6px 10px; border-bottom: 1px solid var(--line); background: rgba(255,255,255,.02); }
.codeblock .cb-hd .lang { font-family: var(--mono); font-size: 11px; color: var(--text-4); }
.codeblock .cb-hd .title { font-size: 12px; color: var(--text-3); }
.codeblock .cb-hd .spacer { flex: 1; }
.codeblock .copy { font-size: 11px; padding: 2px 9px; border-radius: 6px; border: 1px solid var(--line-2); background: var(--panel-2); color: var(--text-2); cursor: pointer; }
.codeblock .copy:hover { border-color: var(--brand); color: #cfe2ff; }
.codeblock pre { margin: 0; padding: 12px 14px; overflow: auto; font-family: var(--mono); font-size: 12.5px; line-height: 1.7; color: #cfe2ff; }
.codeblock code { font-family: inherit; }
code.inline { font-family: var(--mono); font-size: 12.5px; background: var(--panel-3); border: 1px solid var(--line); border-radius: 6px; padding: 1px 6px; color: #cfe2ff; }

table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 13px; }
th, td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
th { background: rgba(255,255,255,.02); color: var(--text-2); font-weight: 600; }
td code, th code { white-space: nowrap; }

.badge { display: inline-flex; align-items: center; gap: 5px; font-size: 11px; padding: 1.5px 8px; border-radius: 999px; border: 1px solid var(--line-2); color: var(--text-2); }
.badge.ok { color: var(--ok); border-color: rgba(52,211,153,.45); }
.badge.warn { color: var(--warn); border-color: rgba(251,191,36,.45); }
.badge.bad { color: var(--danger); border-color: rgba(248,113,113,.45); }
.badge.brand { color: var(--brand-2); border-color: rgba(34,211,238,.45); }

.repo { display: grid; gap: 8px; margin: 14px 0; }
.repo .r { display: flex; align-items: flex-start; gap: 10px; border: 1px solid var(--line); border-radius: var(--r-sm); padding: 10px 12px; background: var(--panel); }
.repo .r .n { font-weight: 600; min-width: 190px; }
.repo .r .u { font-family: var(--mono); font-size: 12px; color: var(--text-3); word-break: break-all; }

.two { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.grid3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.muted { color: var(--text-3); }
.small { font-size: 12px; }
.mono { font-family: var(--mono); }
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0; }

.topgrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 12px; margin: 18px 0; }
.tcard { display: block; border: 1px solid var(--line); border-radius: var(--r); padding: 14px 15px; background: linear-gradient(180deg, rgba(20,29,42,.7), rgba(15,22,33,.7)); }
.tcard:hover { border-color: var(--brand); text-decoration: none; }
.tcard .t { font-weight: 600; color: var(--text); }
.tcard .d { color: var(--text-3); font-size: 12.5px; margin-top: 6px; }

/* 章节底部翻页 */
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 46px; padding-top: 18px; border-top: 1px solid var(--line); }
.pager a { display: block; border: 1px solid var(--line); border-radius: var(--r-sm); padding: 10px 14px; max-width: 48%; }
.pager a:hover { border-color: var(--brand); text-decoration: none; }
.pager a .d { font-size: 11.5px; color: var(--text-4); }
.pager a .t { color: var(--text); font-weight: 600; }
.pager .spacer { flex: 1; }

/* ---------------------------------------------------------------- 响应式 */
@media (max-width: 1024px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: fixed; left: 0; top: 0; z-index: 60; width: 280px; transform: translateX(-100%); transition: transform .2s ease; box-shadow: 0 0 40px rgba(0,0,0,.5); }
  body.nav-open .sidebar { transform: none; }
  .menu-btn { display: inline-flex; align-items: center; gap: 6px; padding: 5px 10px; border-radius: 8px; border: 1px solid var(--line-2); background: var(--panel-2); color: var(--text); cursor: pointer; }
  .doc { padding: 22px 18px 80px; }
  .doc-top { padding: 10px 16px; }
  .two, .grid3 { grid-template-columns: 1fr; }
  .repo .r { flex-direction: column; gap: 2px; }
}