:root{
  --ink:#000000;
  --paper:#ffffff;
  --r:10px;
  --line:2px solid #000000;
  --rail:264px;
  --pad:clamp(20px,4vw,60px);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  overflow-x:clip;
  background:var(--paper);
  color:var(--ink);
  font-family:"DM Sans","Nunito",system-ui,-apple-system,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  font-size:17px;
  line-height:1.75;
}
h1,h2,h3,.brand-name,.foot-name{font-family:"Nunito","DM Sans",system-ui,-apple-system,"PingFang SC","Microsoft YaHei",sans-serif;font-weight:900}
a{color:inherit}
img{max-width:100%}
:focus-visible{outline:3px solid #000000;outline-offset:3px}

/* 左侧固定竖排栏 */
.shell-head{
  position:fixed;
  top:0;left:0;bottom:0;
  width:var(--rail);
  z-index:30;
  display:flex;
  flex-direction:column;
  gap:22px;
  padding:34px 26px 30px;
  background:var(--paper);
  border-right:var(--line);
}
.brand{display:flex;flex-direction:column;gap:12px;text-decoration:none;color:var(--ink)}
.brand-mark{width:62px;height:62px;border-radius:50%;border:var(--line);object-fit:cover}
.brand-name{font-size:1.45rem;line-height:1.14;letter-spacing:-.035em}
.head-nav{display:flex;flex-direction:column;margin-top:4px}
.head-nav a{
  display:block;
  padding:11px 12px;
  font-size:.98rem;
  line-height:1.35;
  text-decoration:none;
  border-radius:var(--r);
  transition:background .18s ease,color .18s ease,transform .18s ease;
}
.head-nav a:hover,.head-nav a:focus-visible{background:var(--ink);color:var(--paper);transform:translateX(3px)}
.head-nav a.is-on{background:var(--ink);color:var(--paper)}
.head-contact{
  margin-top:auto;
  display:flex;align-items:center;justify-content:center;
  min-height:46px;
  border:var(--line);
  border-radius:999px;
  font-weight:700;
  text-decoration:none;
  transition:background .18s ease,color .18s ease;
}
.head-contact:hover{background:var(--ink);color:var(--paper)}

/* 主体骨架 */
main{margin-left:var(--rail)}
.wrap{max-width:1180px;margin:0 auto;padding:0 var(--pad)}
.hero{
  min-height:70vh;
  display:flex;
  flex-direction:column;
  justify-content:flex-end;
  padding:clamp(48px,9vw,110px) 0 0;
}
.hero h1{
  margin:0 0 clamp(26px,5vw,56px);
  font-size:clamp(2.6rem,7vw,6rem);
  line-height:.96;
  letter-spacing:-.05em;
  word-break:break-word;
  text-wrap:balance;
}
.band{
  height:clamp(54px,9vw,110px);
  background:var(--ink);
  clip-path:polygon(0 78%,100% 0,100% 100%,0 100%);
  margin-bottom:clamp(36px,6vw,68px);
  animation:cut 9s ease-in-out infinite alternate;
}
@keyframes cut{
  from{clip-path:polygon(0 86%,100% 0,100% 100%,0 100%)}
  to{clip-path:polygon(0 8%,100% 100%,100% 100%,0 100%)}
}

/* 正文与右栏 */
.body-grid{
  display:grid;
  grid-template-columns:minmax(0,1fr) 254px;
  gap:clamp(24px,4vw,52px);
  align-items:start;
  padding-bottom:clamp(48px,8vw,100px);
}
.prose{min-width:0;font-size:17.5px}
.prose > div{scroll-margin-top:96px;padding-top:clamp(26px,4vw,42px);border-top:var(--line)}
.prose > div:first-child{border-top:0;padding-top:0}
.prose h2{
  margin:0 0 .45em;
  font-size:clamp(1.5rem,3vw,2.2rem);
  line-height:1.14;
  letter-spacing:-.035em;
}
.prose h3{margin:1.5em 0 .5em;font-size:1.18rem;line-height:1.3;font-weight:900}
.prose p{margin:0 0 1.05em}
.subtitle{font-size:1rem;line-height:1.5}
.prose p.subtitle{margin:-.1em 0 1.15em;font-weight:700;font-size:1.03rem}
.prose a{text-decoration:underline;text-decoration-thickness:2px;text-underline-offset:3px}
.prose a:hover{background:var(--ink);color:var(--paper);text-decoration:none}
.prose ul,.prose ol{margin:0 0 1.1em;padding-left:1.3em}
.prose li{margin:.35em 0}
.prose blockquote{margin:0 0 1.2em;padding:14px 20px;border-left:7px solid var(--ink);background:#f5f5f5}
.prose blockquote p:last-child{margin:0}
.prose img{width:auto;height:auto;border:var(--line);border-radius:var(--r);margin:.4em 0 1.15em}
.prose table{width:100%;border-collapse:collapse;margin:0 0 1.2em;font-size:.98rem}
.prose th,.prose td{border:1px solid #000000;padding:9px 12px;text-align:left}
.prose hr{border:0;border-top:var(--line);margin:2em 0}
.prose code{
  font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  background:#f0f0f0;padding:1px 5px;border-radius:4px;font-size:.92em;
}

.rail{
  position:sticky;
  top:28px;
  border:var(--line);
  border-radius:var(--r);
  padding:20px 18px 8px;
  background:var(--paper);
}
.rail-h{margin:0;font-size:1.02rem;letter-spacing:.02em}
.rail .subtitle{margin:.35em 0 14px;font-size:.82rem;line-height:1.45;font-weight:500;opacity:.62}
.rail-list{list-style:none;margin:0;padding:0}
.rail-list li{border-top:1px solid #0000001f}
.rail-list a{display:block;padding:10px 0;font-size:.94rem;line-height:1.4;text-decoration:none}
.rail-list a:hover,.rail-list a.is-on{font-weight:700;text-decoration:underline;text-underline-offset:3px}

/* 页脚 */
.shell-foot{
  margin-left:var(--rail);
  background:var(--ink);
  color:var(--paper);
  display:grid;
  grid-template-columns:1.15fr .85fr;
  gap:clamp(24px,5vw,64px);
  padding:clamp(40px,6vw,72px) var(--pad) 0;
}
.foot-name{margin:0;font-size:clamp(1.6rem,4vw,2.5rem);line-height:1.06;letter-spacing:-.04em}
.foot-desc{margin:.75em 0 0;font-size:.94rem;line-height:1.6;opacity:.78;max-width:34ch}
.foot-links dl{display:grid;grid-template-columns:auto 1fr;column-gap:14px;margin:0}
.foot-links dt{font-size:.76rem;letter-spacing:.1em;opacity:.5;padding-top:1.2em;font-variant-numeric:tabular-nums}
.foot-links dd{margin:0}
.foot-links dd a{
  display:flex;align-items:center;
  min-height:44px;
  padding:.35em 0;
  color:var(--paper);
  text-decoration:none;
  border-bottom:1px solid #ffffff26;
  font-size:1rem;
  transition:padding .18s ease,background .18s ease,color .18s ease;
}
.foot-links dd a:hover{background:var(--paper);color:var(--ink);padding-left:8px}
.foot-base{
  grid-column:1/-1;
  display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;
  gap:12px;
  margin:clamp(30px,5vw,56px) 0 0;
  border-top:1px solid #ffffff33;
  padding:18px 0 26px;
  font-size:.9rem;
}
.foot-base .copy{margin:0;opacity:.75}
.to-top{
  display:inline-flex;align-items:center;
  min-height:44px;padding:0 16px;
  border:1px solid #ffffff59;border-radius:999px;
  color:var(--paper);text-decoration:none;
  transition:background .18s ease,color .18s ease;
}
.to-top:hover{background:var(--paper);color:var(--ink)}

/* 移动端 */
@media (max-width:900px){
  .shell-head{
    position:static;
    width:auto;
    display:grid;
    grid-template-columns:1fr auto;
    align-items:center;
    gap:10px 14px;
    padding:16px 18px;
    border-right:0;
    border-bottom:var(--line);
  }
  .brand{flex-direction:row;align-items:center;gap:10px}
  .brand-mark{width:44px;height:44px}
  .brand-name{font-size:1.12rem}
  .head-nav{
    grid-column:1/-1;
    flex-direction:row;
    gap:8px;
    margin:0;
    overflow-x:auto;
    padding-bottom:4px;
  }
  .head-nav a{
    flex:0 0 auto;
    display:flex;align-items:center;
    min-height:42px;
    padding:0 13px;
    border:var(--line);
    border-radius:999px;
    font-size:.92rem;
    white-space:nowrap;
  }
  .head-nav a:hover{transform:none}
  .head-contact{margin:0;min-height:42px;padding:0 18px;font-size:.92rem}
  main,.shell-foot{margin-left:0}
  .hero{min-height:0;padding:34px 0 0}
  .hero h1{font-size:clamp(2.3rem,10.5vw,3.6rem);margin-bottom:22px}
  .band{height:52px;margin-bottom:32px;animation:none}
  .body-grid{grid-template-columns:minmax(0,1fr);gap:26px;padding-bottom:44px}
  .prose{font-size:17px}
  .rail{position:static}
  .shell-foot{grid-template-columns:1fr;gap:26px;padding:34px 18px 0}
  .foot-base{padding-bottom:22px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none!important;transition:none!important}
}

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