:root{
  --bg:#f6f8fa; --panel:#fff; --ink:#1f2328; --muted:#57606a; --line:#d8dee4;
  --brand:#0b66c3; --brand-soft:#e7f0fb; --brand-dk:#0a4f96;
  --codebg:#f3f5f7; --tcode:#bf3989; --warn:#9a6700;
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  line-height:1.75;font-size:15px;-webkit-text-size-adjust:100%}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}

/* 顶栏 */
header.top{background:linear-gradient(120deg,#0b66c3,#0a4f96);color:#fff;padding:26px 32px 22px;position:sticky;top:0;z-index:30;
  box-shadow:0 2px 10px rgba(16,22,26,.12)}
header.top .hd{max-width:1320px;margin:0 auto;display:flex;align-items:center;gap:16px;flex-wrap:wrap}
header.top h1{margin:0;font-size:21px;font-weight:700;letter-spacing:.4px}
header.top .sp{flex:1}
header.top .meta{opacity:.86;font-size:12.5px}
header.top a{color:#fff;text-decoration:none}
header.top a:hover{text-decoration:underline}
.hd-search{position:relative}
.hd-search input{width:230px;padding:7px 12px;border-radius:8px;border:1px solid rgba(255,255,255,.35);
  background:rgba(255,255,255,.16);color:#fff;font-size:13.5px;outline:none}
.hd-search input::placeholder{color:rgba(255,255,255,.72)}
.hd-search input:focus{background:rgba(255,255,255,.26);border-color:rgba(255,255,255,.6)}

/* 布局 */
.wrap{display:flex;max-width:1320px;margin:0 auto;padding:0 20px 64px;align-items:flex-start}
nav.toc{position:sticky;top:74px;align-self:flex-start;width:262px;flex:0 0 262px;
  background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:12px 8px;margin:22px 20px 0 0;
  max-height:calc(100vh - 96px);overflow:auto;font-size:13px}
nav.toc::-webkit-scrollbar{width:7px}
nav.toc::-webkit-scrollbar-thumb{background:#d6dce2;border-radius:4px}
.t-cap{font-weight:700;color:var(--ink);padding:6px 10px 8px;font-size:12px;letter-spacing:.5px;
  text-transform:uppercase;border-bottom:1px solid var(--line);margin-bottom:6px}
.t-cap::after{content:none}
nav.toc ul{list-style:none;margin:0;padding:0}
nav.toc ul.t-sub{padding-left:0}
nav.toc ul.t-sub ul{padding-left:14px;border-left:1px solid var(--line);margin-left:8px}
nav.toc li{margin:0}
nav.toc a{display:flex;align-items:flex-start;gap:4px;color:var(--muted);padding:5px 8px;border-radius:6px;line-height:1.5}
nav.toc a:hover{background:var(--brand-soft);color:var(--brand);text-decoration:none}
nav.toc a.t-cur{background:var(--brand-soft);color:var(--brand-dk);font-weight:600}
.t-ar{width:12px;flex:0 0 12px;color:#9aa4ae;font-size:10px;line-height:1.9;cursor:pointer;user-select:none}
.t-ar-e{visibility:hidden}
.t-t{flex:1;min-width:0;word-break:break-word}
.t-sub.hide{display:none}

/* 主体 */
main{flex:1;min-width:0;margin-top:22px}
.crumb{font-size:12.5px;color:var(--muted);margin:0 0 10px}
.crumb a{color:var(--muted)}
.crumb a:hover{color:var(--brand)}
.crumb span.sep{margin:0 6px;color:#c2c9d0}
article{background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:26px 30px 30px}
article h1{font-size:24px;margin:0 0 4px;border-left:4px solid var(--brand);padding-left:11px;line-height:1.35}
article h2{font-size:19px;margin:26px 0 8px;border-left:4px solid var(--brand);padding-left:10px;line-height:1.4}
article h3{font-size:16px;margin:20px 0 7px;color:var(--brand-dk)}
article h4{font-size:14.5px;margin:15px 0 6px}
article p{margin:10px 0}
article ul,article ol{margin:10px 0;padding-left:24px}
article li{margin:5px 0}
article p,article li{font-size:15px;line-height:1.8;color:#24292f}
article blockquote{margin:12px 0;padding:9px 14px;border-left:3px solid #d0a215;background:#fff8e1;
  border-radius:0 7px 7px 0;color:#6a5200}
article code{background:var(--codebg);color:var(--tcode);padding:1px 6px;border-radius:4px;font-size:12.5px;
  font-family:"SF Mono",Menlo,Consolas,monospace}
article pre{background:#0d1117;color:#e6edf3;border-radius:8px;padding:14px 16px;overflow:auto;font-size:12.5px;line-height:1.55;
  font-family:"SF Mono",Menlo,Consolas,monospace}
article pre code{background:none;color:inherit;padding:0}
article table{border-collapse:collapse;width:100%;margin:12px 0;font-size:13px;display:block;overflow-x:auto}
article th,article td{border:1px solid var(--line);padding:7px 10px;text-align:left;vertical-align:top}
article th{background:var(--brand-soft);color:var(--brand-dk);font-weight:600}
article tr:nth-child(even) td{background:#fbfcfd}
article img{max-width:100%;height:auto;border-radius:8px;border:1px solid var(--line);
  display:block;margin:12px 0;background:var(--bg);box-shadow:0 1px 3px rgba(16,22,26,.06);
  transition:box-shadow .18s ease}
article img:hover{box-shadow:0 4px 14px rgba(16,22,26,.13)}
/* 懒加载占位：未加载时保持比例不跳动 */
article img[loading="lazy"]{background-image:linear-gradient(100deg,#f3f5f7 30%,#e9edf1 50%,#f3f5f7 70%);
  background-size:220% 100%;animation:czzyShimmer 1.4s infinite linear}
@keyframes czzyShimmer{0%{background-position:180% 0}100%{background-position:-40% 0}}
@media (prefers-reduced-motion:reduce){article img[loading="lazy"]{animation:none}}
article a{color:#1677ff;overflow-wrap:anywhere;word-break:break-word}
/* 长 URL 不撑破容器 */
article p,article li,article td,article th{overflow-wrap:anywhere;word-break:break-word}
/* 表格：横向滚动而不是撑破页面 */
article table{display:block;width:100%;max-width:100%;overflow-x:auto;-webkit-overflow-scrolling:touch}
article th,article td{min-width:80px}
/* 代码块：横向滚动 */
article pre{max-width:100%;overflow-x:auto;-webkit-overflow-scrolling:touch}
article pre code{word-break:normal;white-space:pre}

/* 目录卡片 */
.cat-tip{color:var(--muted);font-size:13.5px;margin:4px 0 12px}
ul.cat-l{list-style:none;padding:0;margin:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(212px,1fr));gap:9px}
ul.cat-l>li{background:#fbfcfd;border:1px solid var(--line);border-radius:8px;padding:9px 12px;margin:0}
ul.cat-l>li>a{font-weight:600;color:var(--brand-dk);display:block}
ul.cat-l>li>a:hover{color:var(--brand)}
li.grp>span.grp-t{font-weight:600;color:var(--brand-dk);display:block;margin-bottom:4px}
ul.grp-c{list-style:none;padding:0;margin:0;border-left:2px solid var(--line);padding-left:9px}
ul.grp-c li{margin:2px 0;font-size:13px}

/* 上下篇 */
.pn{display:flex;gap:12px;margin-top:20px;flex-wrap:wrap}
.pn a{flex:1 1 240px;background:var(--panel);border:1px solid var(--line);border-radius:9px;padding:11px 14px;
  font-size:13.5px;color:var(--muted);text-decoration:none}
.pn a:hover{border-color:var(--brand);color:var(--brand);text-decoration:none}
.pn a b{display:block;color:var(--ink);font-size:13px;font-weight:600;margin-bottom:2px}
.pn a.pn-r{text-align:right}
.pn a.pn-none{opacity:.5;pointer-events:none}
.foot{text-align:center;color:var(--muted);font-size:12.5px;margin-top:26px;line-height:1.9}

/* 首页 */
.hero{background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:26px 30px;margin-top:22px}
.hero h2{margin:0 0 6px;font-size:20px;border-left:4px solid var(--brand);padding-left:10px}
.hero p.lead{color:var(--muted);font-size:13.5px;margin:2px 0 14px}
.grids{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:12px}
.gcard{background:var(--panel);border:1px solid var(--line);border-radius:9px;padding:14px 16px}
.gcard h3{margin:0 0 6px;font-size:15.5px;color:var(--brand-dk)}
.gcard h3 a{color:var(--brand-dk)}
.gcard ul{list-style:none;padding:0;margin:0;font-size:13px}
.gcard li{padding:3px 0;border-bottom:1px dashed #e6eaee}
.gcard li:last-child{border-bottom:0}
.gcard .more{font-size:12.5px;color:var(--muted);display:inline-block;margin-top:6px}
.stat{display:flex;gap:22px;flex-wrap:wrap;margin:10px 0 0;font-size:13px;color:var(--muted)}
.stat b{color:var(--brand-dk);font-size:17px;display:block;line-height:1.3}

/* 移动端 */
@media (max-width:900px){
  .wrap{flex-direction:column;padding:0 14px 44px}
  nav.toc{position:static;width:auto;flex:1 1 auto;margin:16px 0 0;max-height:none;
    max-height:42vh;overflow:auto}
  header.top{padding:16px 16px 14px}
  header.top h1{font-size:18px}
  .hd-search input{width:100%}
  .hd-search{flex:1 1 100%}
  article{padding:18px 16px 22px}
  article h1{font-size:20px;line-height:1.4}
  article h2{font-size:17px;margin:22px 0 8px}
  article h3{font-size:15.5px}
  article p,article li{font-size:15px;line-height:1.85}
  article img{margin:12px 0;border-radius:6px}
  ul.cat-l{grid-template-columns:1fr;gap:8px}
  ul.cat-l>li{padding:11px 13px}
  .pn a{flex:1 1 100%;padding:13px 15px}
  .crumb{font-size:12px;line-height:1.7;margin-bottom:8px}
  /* 树节点触达友好 */
  nav.toc a{padding:8px 8px;font-size:14px;line-height:1.5}
  nav.toc ul.t-sub ul{padding-left:12px;margin-left:7px}
  .t-ar{font-size:12px;line-height:1.6;width:14px;flex:0 0 14px}
  /* 顶栏更紧凑 */
  header.top{padding:12px 14px 11px}
  header.top h1{font-size:17px}
  header.top .meta{font-size:11.5px}
  .hd-search input{height:36px}
  /* 正文底部留白 */
  .foot{font-size:11.5px;margin-top:20px}
}
/* 移动端：目录默认收起二级及以下，正文优先 */
@media (max-width:900px){
  nav.toc ul.t-sub ul{display:none}
  nav.toc ul.t-sub.t-open>li.t-cur>ul{display:block}
  nav.toc .t-cap{display:flex;align-items:center;justify-content:space-between;cursor:pointer}
  nav.toc .t-cap::after{content:'展开 / 收起';font-weight:400;text-transform:none;letter-spacing:0;
    font-size:12px;color:var(--muted)}
  nav.toc.toc-fold{max-height:none}
  nav.toc.toc-fold ul{display:none}
  nav.toc.toc-fold ul.t-open{display:block}
  nav.toc.toc-fold .t-cap::after{content:'展开 / 收起'}
}