:root{
  --paper:#f5f1ea;--panel:#fffdf9;--ink:#262119;--muted:#756d5f;
  --line:#dfd6c7;--accent:#bf5b2a;--green:#4a7c59;
  --serif:"Noto Serif SC","Songti SC",Georgia,serif;
  --sans:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",Arial,sans-serif;
}
*{box-sizing:border-box}
body{margin:0;overflow-x:hidden;background:var(--paper);color:var(--ink);font:15px/1.75 var(--sans)}
body:before{content:"";position:fixed;inset:0;z-index:-1;pointer-events:none;background:radial-gradient(900px 520px at 5% 0,rgba(191,91,42,.07),transparent 62%),radial-gradient(760px 460px at 96% 8%,rgba(74,124,89,.06),transparent 58%)}
a{color:inherit}.shell{width:min(960px,calc(100% - 36px));margin:auto}
.top{display:flex;align-items:center;gap:22px;padding:24px 0 18px;border-bottom:1px solid var(--line)}
.brand{text-decoration:none;font:700 22px/1 var(--serif);letter-spacing:.15em}.top nav{margin-left:auto;display:flex;gap:16px;flex-wrap:wrap}.top nav a,.lang{font-size:12px;color:var(--muted);text-decoration:none}.top nav a:hover,.lang:hover{color:var(--accent)}
.lang{border:1px solid var(--line);border-radius:99px;padding:4px 10px;background:rgba(255,255,255,.35)}
.hero{padding:72px 0 46px;border-bottom:1px solid var(--line)}.eyebrow{margin:0 0 10px;color:var(--accent);font-size:11px;letter-spacing:.14em}.hero h1{margin:0;font:600 clamp(38px,7vw,66px)/1.08 var(--serif);letter-spacing:-.04em}.hero p{max-width:700px;margin:18px 0 0;color:var(--muted);font-size:16px}
.content{display:grid;grid-template-columns:220px minmax(0,1fr);gap:52px;padding:46px 0 70px}.toc{position:sticky;top:20px;align-self:start;border-top:2px solid var(--ink);padding-top:12px}.toc a{display:block;padding:7px 0;color:var(--muted);font-size:12px;text-decoration:none}.toc a:hover{color:var(--accent)}
.article{min-width:0}.article section{padding:0 0 34px;margin:0 0 34px;border-bottom:1px solid var(--line)}.article section:last-child{border-bottom:0}.article h2{margin:0 0 13px;font:600 26px/1.25 var(--serif)}.article h3{margin:20px 0 7px;font-size:15px}.article p{margin:8px 0;color:var(--muted);overflow-wrap:anywhere}.article ul{margin:10px 0;padding-left:20px;color:var(--muted)}.article strong{color:var(--ink)}
.boundary{padding:16px 18px;border-left:3px solid var(--accent);background:rgba(255,253,249,.68);color:var(--muted)}
.contact{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin-top:14px}.contact a,.contact span{display:block;padding:12px 14px;border:1px solid var(--line);border-radius:10px;background:rgba(255,253,249,.6);text-decoration:none}.contact small{display:block;color:var(--muted)}
footer{display:flex;justify-content:space-between;gap:18px;flex-wrap:wrap;padding:20px 0 32px;border-top:1px solid var(--line);color:var(--muted);font-size:11px}footer a{margin-left:12px}
[data-copy="en"]{display:none}html[data-lang="en"] [data-copy="zh"]{display:none}html[data-lang="en"] [data-copy="en"]{display:block}
@media(max-width:720px){.top{align-items:flex-start}.top nav{display:none}.content{grid-template-columns:1fr;gap:24px}.toc{position:static;display:flex;gap:12px;overflow:auto;border-top:0;border-bottom:1px solid var(--line);padding:0 0 12px}.toc a{white-space:nowrap}.hero{padding:48px 0 34px}.contact{grid-template-columns:1fr}}