@import url('https://fonts.googleapis.com/css2?family=Archivo:wght@300;400;500;600;700&family=Space+Grotesk:wght@300;400;500;600;700&display=swap');

*,*::before,*::after{box-sizing:border-box}

:root{
  --ink:#000;
  --paper:#fff;
  --line:#000;
  --pad:clamp(16px,4vw,48px);
  --gap:16px;
  --r:18px;
  --max:1320px;
}

html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
html.lock{overflow:hidden}

body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:"Archivo","Space Grotesk",Helvetica,Arial,system-ui,sans-serif;
  font-size:17px;
  line-height:1.6;
  letter-spacing:-.01em;
  font-weight:400;
}

img{max-width:100%;height:auto;display:block;border-radius:12px}
a{color:inherit}
:focus-visible{outline:2px solid var(--ink);outline-offset:3px}

.n{font-family:"Space Grotesk","Archivo",sans-serif;font-size:16px;font-weight:500;font-variant-numeric:tabular-nums}

/* 头部：品牌行在上，菜单行在下 */
.hdr{position:relative;z-index:30;background:var(--paper);border-bottom:2px solid var(--line)}
@media(min-width:901px){.hdr{position:sticky;top:0}}

.hdr-top{
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  max-width:var(--max);margin:0 auto;padding:12px var(--pad);
}

.brand{
  display:inline-flex;align-items:center;min-height:44px;
  text-decoration:none;font-family:"Space Grotesk","Archivo",sans-serif;
  font-weight:700;font-size:clamp(17px,2vw,21px);letter-spacing:-.02em;
}

.hdr-tools{display:flex;align-items:center;gap:8px}

.cta{
  display:inline-flex;align-items:center;min-height:44px;padding:0 16px;
  background:var(--ink);color:var(--paper);text-decoration:none;
  border-radius:999px;font-size:16px;font-weight:600;white-space:nowrap;
}

.burger{
  display:inline-flex;align-items:center;gap:8px;min-height:44px;padding:0 14px;
  border:1px solid var(--line);border-radius:999px;background:var(--paper);
  color:var(--ink);font:inherit;font-size:16px;font-weight:600;cursor:pointer;
}
.burger-bars{display:block;width:16px;height:10px;border-top:2px solid;border-bottom:2px solid}

.hdr-nav{padding:0 var(--pad);border-top:1px solid var(--line)}
.hdr-nav p{
  display:flex;align-items:center;gap:4px;margin:0 auto;max-width:var(--max);
  padding:6px 0;overflow-x:auto;scrollbar-width:thin;
}
.hdr-nav a{
  display:inline-flex;align-items:center;gap:6px;min-height:40px;padding:0 10px;
  text-decoration:none;white-space:nowrap;border-radius:999px;font-size:16px;
}
.hdr-nav a:hover{background:var(--ink);color:var(--paper)}

/* 全屏遮罩菜单 */
.ovl{
  position:fixed;inset:0;z-index:60;background:var(--ink);color:var(--paper);
  display:flex;flex-direction:column;padding:var(--pad);overflow-y:auto;
}
.ovl[hidden]{display:none}

.ovl-top{display:flex;align-items:center;justify-content:space-between;gap:12px;border-bottom:1px solid #fff;padding-bottom:14px}
.ovl-brand{font-family:"Space Grotesk","Archivo",sans-serif;font-weight:700;font-size:18px}
.ovl-x{
  min-height:44px;padding:0 16px;border:1px solid #fff;border-radius:999px;
  background:transparent;color:#fff;font:inherit;font-size:16px;font-weight:600;cursor:pointer;
}

.ovl-list{display:flex;flex-direction:column;margin-top:20px}
.ovl-list a{
  display:flex;align-items:center;gap:14px;min-height:56px;text-decoration:none;
  border-bottom:1px solid rgba(255,255,255,.35);
  font-family:"Space Grotesk","Archivo",sans-serif;
  font-size:clamp(20px,4vw,32px);font-weight:500;letter-spacing:-.02em;
}
.ovl-list a:hover{background:#fff;color:#000;padding-left:12px}
.ovl-list .n{opacity:.6}

/* 主栅格：内容在左，目录在右 */
.shell{
  display:grid;grid-template-columns:repeat(12,1fr);gap:var(--gap);
  max-width:var(--max);margin:0 auto;padding:0 var(--pad);
}

.doc{grid-column:1/9;min-width:0}

.hero{
  min-height:45vh;display:flex;align-items:flex-end;
  padding:clamp(28px,6vw,72px) 0 clamp(18px,3vw,32px);
  border-bottom:2px solid var(--line);margin-bottom:var(--gap);
}
.hero h1{
  margin:0;font-family:"Space Grotesk","Archivo",sans-serif;
  font-size:clamp(34px,7vw,86px);line-height:.96;letter-spacing:-.035em;
  font-weight:700;word-break:break-word;
}

.doc > *{animation:rise .5s cubic-bezier(.2,.7,.2,1) both}
.doc > *:nth-child(1){animation-delay:.04s}
.doc > *:nth-child(2){animation-delay:.08s}
.doc > *:nth-child(3){animation-delay:.12s}
.doc > *:nth-child(4){animation-delay:.16s}
.doc > *:nth-child(5){animation-delay:.2s}
.doc > *:nth-child(6){animation-delay:.24s}
.doc > *:nth-child(7){animation-delay:.28s}
.doc > *:nth-child(8){animation-delay:.32s}

@keyframes rise{
  from{opacity:0;transform:translateY(10px)}
  to{opacity:1;transform:none}
}

/* 正文分节：描边块，无阴影 */
.doc > article[id]{
  border:1px solid var(--line);border-radius:var(--r);
  padding:clamp(20px,3vw,36px);margin:0 0 var(--gap);
  scroll-margin-top:150px;background:var(--paper);
}

.doc h2{
  margin:0 0 .35em;font-family:"Space Grotesk","Archivo",sans-serif;
  font-size:clamp(22px,3vw,34px);line-height:1.12;letter-spacing:-.02em;font-weight:700;
}
.doc h2 + p,.doc p.subtitle{margin-top:0;opacity:.72;max-width:56ch}
.doc h3{margin:1.6em 0 .4em;font-size:19px;font-weight:700;letter-spacing:-.01em}
.doc p{margin:0 0 1.1em}
.doc p:last-child{margin-bottom:0}
.doc ul,.doc ol{margin:0 0 1.1em;padding-left:1.2em}
.doc li{margin:.35em 0}
.doc a{text-decoration:underline;text-underline-offset:3px}
.doc a:hover{background:var(--ink);color:var(--paper);text-decoration:none}
.doc strong{font-weight:700}
.doc blockquote{margin:1.2em 0;padding-left:16px;border-left:3px solid var(--ink)}
.doc table{width:100%;border-collapse:collapse;font-size:16px}
.doc th,.doc td{border-bottom:1px solid var(--line);padding:10px;text-align:left}

/* 右侧目录 */
.side{
  grid-column:9/13;align-self:start;position:sticky;top:150px;
  padding-top:14px;border-top:2px solid var(--line);min-width:0;
}
.side h2{margin:0 0 .3em;font-size:18px;font-weight:700;letter-spacing:-.01em}
.side .subtitle{margin:0 0 16px;font-size:16px;line-height:1.5;opacity:.7}
.side-list{list-style:none;margin:0;padding:0;border-top:1px solid var(--line)}
.side-list li{border-bottom:1px solid var(--line)}
.side-list a{
  display:flex;align-items:center;gap:10px;min-height:44px;padding:10px 0;
  text-decoration:none;font-size:16px;
}
.side-list a:hover{padding-left:8px}
.side-list .n{opacity:.45}

/* 页脚：三列说明列 */
.ft{border-top:2px solid var(--line);margin-top:40px}
.ft-in{
  display:grid;grid-template-columns:repeat(3,1fr);gap:var(--gap);
  max-width:var(--max);margin:0 auto;padding:32px var(--pad) 28px;
}
.ft dl{margin:0}
.ft dt{
  font-size:16px;font-weight:700;border-bottom:1px solid var(--line);
  padding-bottom:8px;margin-bottom:4px;letter-spacing:-.01em;
}
.ft dd{margin:0}
.ft dd a{display:inline-flex;align-items:center;min-height:40px;text-decoration:none;font-size:16px}
.ft dd a:hover{text-decoration:underline;text-underline-offset:3px}
.ft-base{
  max-width:var(--max);margin:0 auto;padding:16px var(--pad) 28px;
  border-top:1px solid var(--line);text-align:center;font-size:16px;opacity:.8;
}

@media(max-width:900px){
  .shell{grid-template-columns:1fr;padding-bottom:8px}
  .doc,.side{grid-column:1/-1}
  .hero{min-height:0;padding:32px 0 20px}
  .side{position:static;order:2;margin-top:20px}
  .ft-in{grid-template-columns:1fr;gap:20px}
  .doc > *{animation-duration:.35s}
}

@media(max-width:420px){
  .brand{font-size:17px}
  .cta{padding:0 12px}
  .burger{padding:0 12px}
  .hero h1{letter-spacing:-.03em}
}

@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .doc > *{animation:none}
  *{transition:none!important}
}

button[aria-expanded]{min-width:44px;min-height:44px}