:root{
  --blue:#3bb1ff;
  --red:#ff5252;
  --ink:#000000;
  --paper:#ffffff;
  --tint:#e9f6ff;
  --tint-r:#ffe7e7;
  --rail:236px;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  font-family:"Inter",system-ui,-apple-system,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;
  font-size:17px;
  line-height:1.65;
  color:var(--ink);
  background:var(--tint);
}
img{max-width:100%}
a{color:var(--ink)}
:focus-visible{outline:3px solid var(--red);outline-offset:2px}

.skip{
  position:absolute;top:-70px;left:10px;z-index:99;
  padding:10px 16px;border:3px solid var(--ink);border-radius:999px;
  background:var(--red);font-weight:700;text-decoration:none;
  transition:top .15s ease;
}
.skip:focus{top:10px}

/* 左侧固定竖排胶囊导航 */
.rail{
  position:fixed;top:0;bottom:0;left:0;width:var(--rail);z-index:40;
  display:flex;flex-direction:column;gap:14px;
  padding:16px 14px;background:var(--paper);
  border-right:3px solid var(--ink);overflow-y:auto;
}
.rail-brand{
  display:flex;align-items:center;justify-content:center;text-align:center;
  min-height:48px;padding:8px 12px;
  background:var(--blue);border:3px solid var(--ink);border-radius:999px;
  box-shadow:4px 4px 0 var(--ink);
  font-size:18px;font-weight:700;letter-spacing:-.01em;text-decoration:none;
}
.rail-list{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:10px}
.pill{
  display:flex;align-items:center;min-height:44px;padding:10px 14px;
  background:var(--paper);border:3px solid var(--ink);border-radius:999px;
  box-shadow:4px 4px 0 var(--ink);
  font-size:16px;font-weight:600;text-decoration:none;
  transition:transform .15s ease,box-shadow .15s ease,background .15s ease;
}
.pill:hover,.pill:focus-visible{background:var(--red);transform:translate(-2px,-2px);box-shadow:6px 6px 0 var(--ink)}
.rail-list li:first-child .pill{background:var(--blue)}

/* 全宽蒙版大图 hero */
.hero{
  position:relative;margin-left:var(--rail);
  min-height:45vh;display:flex;align-items:flex-end;
  padding:42px 32px;overflow:hidden;
  background:var(--blue);border-bottom:3px solid var(--ink);
}
.hero-media{position:absolute;inset:0}
.hero-media img{display:block;width:100%;height:100%;max-width:none;object-fit:cover}
.hero-veil{position:absolute;inset:0;background:rgba(0,0,0,.44)}
.hero-mark{
  position:absolute;top:4px;left:20px;
  max-width:calc(100% - 40px);overflow:hidden;
  font-size:clamp(52px,11vw,168px);font-weight:700;line-height:.9;
  letter-spacing:-.05em;white-space:nowrap;
  color:#fff;-webkit-text-stroke:2px var(--ink);
  opacity:.92;pointer-events:none;
}
.hero-copy{position:relative;z-index:2;max-width:920px}
.hero h1{
  margin:0;display:inline-block;
  padding:12px 18px;background:var(--paper);
  border:3px solid var(--ink);border-radius:18px;
  box-shadow:6px 6px 0 var(--ink);
  font-size:clamp(26px,4.4vw,50px);line-height:1.12;letter-spacing:-.02em;
}

/* 正文区 */
main{margin-left:var(--rail);padding:26px 32px 46px;background:var(--tint)}
.board{display:grid;grid-template-columns:250px minmax(0,1fr);gap:26px;align-items:start}
.toc{
  position:sticky;top:18px;max-height:calc(100vh - 36px);overflow:auto;
  padding:16px;background:var(--paper);
  border:3px solid var(--ink);border-bottom:9px solid var(--red);border-radius:18px;
  box-shadow:5px 5px 0 var(--ink);
}
.toc small{display:block;font-size:16px;font-weight:700;letter-spacing:.08em}
.toc h2{margin:2px 0 12px;font-size:20px;line-height:1.25}
.toc-list{list-style:none;margin:0;padding:0;display:grid;gap:8px}
.toc-list a{
  display:flex;align-items:center;min-height:44px;padding:8px 12px;
  background:var(--tint);border:2px solid var(--ink);border-radius:999px;
  font-size:16px;font-weight:600;text-decoration:none;
  transition:background .15s ease,transform .15s ease;
}
.toc-list a:hover{background:var(--blue);transform:translateX(3px)}

.doc > article{
  margin:0 0 26px;padding:22px;
  background:var(--paper);border:3px solid var(--ink);border-bottom:9px solid var(--blue);
  border-radius:18px;box-shadow:5px 5px 0 var(--ink);
  scroll-margin-top:24px;
}
.doc > article:nth-of-type(even){border-bottom-color:var(--red)}
.doc > article:last-child{margin-bottom:0}
.doc h2{margin:0 0 12px;font-size:clamp(21px,2.3vw,29px);line-height:1.25;letter-spacing:-.01em}
.doc h3{margin:20px 0 8px;font-size:19px;line-height:1.3}
.doc small{display:block;margin-bottom:4px;font-size:16px;font-weight:700;letter-spacing:.06em}
.doc p{margin:0 0 12px}
.doc ul,.doc ol{margin:0 0 12px;padding-left:22px}
.doc li{margin-bottom:6px}
.doc a{text-decoration:underline;text-decoration-thickness:2px;text-underline-offset:3px}
.doc a:hover{background:var(--tint-r)}
.doc img{border:3px solid var(--ink);border-radius:18px}
.doc figure{margin:12px 0}
.doc blockquote{
  margin:0 0 12px;padding:12px 16px;background:var(--tint);
  border-left:8px solid var(--blue);border-radius:0 18px 18px 0;
}
.doc table{width:100%;border-collapse:collapse}
.doc th,.doc td{border:2px solid var(--ink);padding:8px;text-align:left}

/* 页脚 */
.foot{margin-left:var(--rail);padding:30px 32px 22px;background:var(--paper);border-top:3px solid var(--ink)}
.foot-grid{display:grid;grid-template-columns:1.15fr 1fr;gap:22px;align-items:start}
.foot-brand{
  display:block;padding:18px;
  background:var(--blue);border:3px solid var(--ink);border-bottom:9px solid var(--ink);
  border-radius:18px;box-shadow:5px 5px 0 var(--ink);font-style:normal;
}
.foot-brand strong{display:block;margin-bottom:8px;font-size:22px;line-height:1.2}
.foot-brand p{margin:0;font-size:16px}
.foot-nav dl{margin:0}
.foot-nav dt{margin-bottom:10px;font-size:18px;font-weight:700}
.foot-nav dd{margin:0 0 8px}
.foot-nav dd a,.foot-links a{
  display:inline-flex;align-items:center;min-height:44px;padding:8px 14px;
  background:var(--paper);border:3px solid var(--ink);border-radius:999px;
  box-shadow:3px 3px 0 var(--ink);
  font-size:16px;font-weight:600;text-decoration:none;
  transition:transform .15s ease,box-shadow .15s ease,background .15s ease;
}
.foot-nav dd a:hover,.foot-links a:hover{background:var(--red);transform:translate(-2px,-2px);box-shadow:5px 5px 0 var(--ink)}
.foot-sub{
  display:flex;flex-wrap:wrap;gap:12px;margin-top:24px;padding:16px;
  background:var(--tint-r);border:3px solid var(--ink);border-bottom:9px solid var(--red);
  border-radius:18px;box-shadow:5px 5px 0 var(--ink);
}
.foot-sub input{
  flex:1 1 220px;min-height:48px;padding:0 16px;font:inherit;
  background:var(--paper);border:3px solid var(--ink);border-radius:999px;
  color:var(--ink);
}
.foot-sub button{
  min-height:48px;padding:0 24px;font:inherit;font-weight:700;cursor:pointer;
  background:var(--ink);color:#fff;border:3px solid var(--ink);border-radius:999px;
  box-shadow:4px 4px 0 var(--blue);
  transition:background .15s ease,color .15s ease;
}
.foot-sub button:hover{background:var(--red);color:var(--ink)}
.foot-bottom{
  display:flex;flex-wrap:wrap;gap:12px;align-items:center;justify-content:space-between;
  margin-top:22px;padding-top:16px;border-top:3px solid var(--ink);
}
.copy{margin:0;font-size:16px;font-weight:600}
.foot-links{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:10px}

/* 动效 */
.rv{opacity:0;transform:translateY(16px);transition:opacity .5s ease,transform .5s ease}
.rv.in{opacity:1;transform:none}

@media (max-width:900px){
  .rail{
    position:sticky;top:0;inset:auto;width:auto;height:auto;z-index:60;
    flex-direction:row;align-items:center;gap:10px;
    padding:10px 14px;overflow-x:auto;overflow-y:visible;
    border-right:0;border-bottom:3px solid var(--ink);
  }
  .rail-brand{flex:0 0 auto;min-height:44px;padding:6px 12px;font-size:16px;box-shadow:3px 3px 0 var(--ink)}
  .rail-list{flex:1 1 auto;flex-direction:row;gap:8px}
  .pill{white-space:nowrap}
  .hero,main,.foot{margin-left:0}
  .hero{min-height:340px;padding:28px 18px}
  .hero-mark{left:12px;font-size:clamp(40px,13vw,90px)}
  .hero h1{padding:10px 14px}
  main{padding:18px 16px 34px}
  .board{grid-template-columns:1fr;gap:18px}
  .toc{position:static;max-height:none}
  .doc > article{scroll-margin-top:80px;padding:18px}
  .foot{padding:22px 16px 18px}
  .foot-grid{grid-template-columns:1fr}
  .foot-bottom{flex-direction:column;align-items:flex-start}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{transition:none !important;animation:none !important}
  .rv{opacity:1;transform:none}
}

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