:root{
  --ink:#000;
  --paper:#fff;
  --gap:1rem;
  --r:18px;
  --pad:clamp(1rem,4vw,3rem);
  --edge:max(clamp(1rem,4vw,3rem),calc((100vw - 1280px)/2));
  --sh:0 18px 38px -22px rgba(0,0,0,.55),0 2px 6px rgba(0,0,0,.05)
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font:400 1.0625rem/1.7 'Plus Jakarta Sans',system-ui,-apple-system,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;
  overflow-x:hidden
}
img{max-width:100%;height:auto;display:block}
a{color:inherit;text-decoration:none;border-bottom:1px solid currentColor}
a:hover{background:var(--ink);color:var(--paper);border-color:var(--ink)}
:focus-visible{outline:2px solid var(--ink);outline-offset:3px}
p{margin:0 0 1rem}
h1,h2,h3{font-weight:700;line-height:1.1;letter-spacing:-.025em;margin:0 0 .85rem}
strong{font-weight:700}

/* 页头 */
.top{
  display:flex;
  align-items:center;
  gap:1rem;
  padding:.75rem var(--edge);
  border-bottom:1px solid var(--ink);
  background:var(--paper);
  position:relative
}
.wordmark{margin:0;position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);z-index:2}
.wordmark a{display:inline-block;padding:.6rem .35rem;border-bottom:0;font-weight:700;letter-spacing:-.03em;font-size:1.15rem;white-space:nowrap}
.markimg{width:auto;height:26px}
.mainnav{flex:1 1 auto;min-width:0;padding-right:7rem}
.navlist{
  list-style:none;
  margin:0;
  padding:0;
  display:grid;
  grid-auto-flow:column;
  grid-template-columns:1fr 1fr;
  grid-template-rows:repeat(4,auto);
  column-gap:clamp(110px,17vw,260px);
  align-items:center
}
.navitem:nth-child(-n+4){justify-self:end;text-align:right}
.navlist a{display:block;padding:.55rem .7rem;border-bottom:0;font-size:1rem;font-weight:500;white-space:nowrap}
.call{margin:0;flex:0 0 auto}
.call a{display:inline-block;padding:.6rem .95rem;border:1px solid var(--ink);border-radius:999px;font-size:1rem;font-weight:500;white-space:nowrap}

/* 主区 */
.stage{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:var(--gap);
  max-width:1280px;
  margin:0 auto;
  padding:clamp(1.25rem,4vw,2.75rem) var(--pad) clamp(2rem,5vw,3.5rem)
}
.body{grid-column:1/9;min-width:0}
.rail{grid-column:10/13;min-width:0}

/* 首屏 */
.hero{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:var(--gap);
  align-items:center;
  min-height:45vh;
  padding-bottom:clamp(1.5rem,4vw,2.5rem)
}
.hero-media{grid-column:1/7;border-radius:var(--r);overflow:hidden;box-shadow:var(--sh);background:var(--ink)}
.hero-media .ph{display:block;aspect-ratio:4/3;background:linear-gradient(140deg,#000 58%,#262626)}
.hero-img{width:100%;aspect-ratio:4/3;object-fit:cover;transform:scale(1.05);will-change:transform}
.hero-copy{grid-column:7/13;text-align:center}
h1{font-size:clamp(2rem,5.2vw,3.4rem);line-height:1.04;letter-spacing:-.04em;margin:0 0 1rem}
.lede{margin:0 auto;max-width:32ch;font-size:1.0625rem;color:#111}

/* 正文 */
.body{counter-reset:sec}
.body>div{
  counter-increment:sec;
  border-top:1px solid var(--ink);
  padding-block:clamp(2rem,4vw,3.25rem);
  scroll-margin-top:1.5rem;
  overflow-wrap:break-word
}
.body>div::before{
  content:counter(sec,decimal-leading-zero);
  display:block;
  font-size:1rem;
  font-weight:700;
  letter-spacing:.24em;
  margin-bottom:.9rem
}
h2{font-size:clamp(1.4rem,2.6vw,2rem)}
h3{font-size:1.2rem;letter-spacing:-.01em}
h2+hr{border:0;border-top:2px solid var(--ink);margin:0 0 1.4rem}
h3+hr{border:0;border-top:1px solid var(--ink);margin:0 0 1.1rem}
.body>div :is(p,ul,ol,blockquote,dl){max-width:66ch}
.body>div ul,.body>div ol{padding-left:1.2em;margin:0 0 1.05rem}
.body>div li{margin:.35rem 0}
.body>div blockquote{margin:0 0 1.1rem;padding-left:1.1rem;border-left:3px solid var(--ink)}
.body>div p{margin:0 0 1.05rem}

/* 侧栏 */
.rail{
  align-self:start;
  position:sticky;
  top:1.25rem;
  border:1px solid var(--ink);
  border-radius:var(--r);
  padding:1.25rem;
  background:var(--paper);
  box-shadow:var(--sh)
}
.rail h2{font-size:1rem;letter-spacing:.18em;text-transform:none;margin:0 0 .5rem}
.rail hr{border:0;border-top:1px solid var(--ink);margin:0 0 .9rem}
.raillist{list-style:none;margin:0;padding:0}
.raillist a{display:block;padding:.62rem 0;border-bottom:1px solid var(--ink);font-size:1rem}
.raillist li:last-child a{border-bottom:0}
.totop{margin:0}
.rail .totop{margin-top:1rem}
.totop a{display:block;padding:.7rem 0;border-bottom:0;font-weight:500}

/* 页脚 */
.foot{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:var(--gap);
  align-items:start;
  border-top:2px solid var(--ink);
  padding:clamp(2rem,4vw,3rem) var(--edge) 2.5rem
}
.foot>*{min-width:0}
.foot-brand{margin:0;font-weight:700;font-size:1.15rem;letter-spacing:-.02em}
.sub{display:flex;flex-wrap:wrap;gap:.5rem;margin:1rem 0 0}
.sub input{
  flex:1 1 8rem;
  min-width:0;
  min-height:44px;
  padding:0 1rem;
  border:1px solid var(--ink);
  border-radius:999px;
  background:var(--paper);
  color:var(--ink);
  font:inherit;
  font-size:1rem
}
.sub button{
  min-height:44px;
  padding:0 1.15rem;
  border:1px solid var(--ink);
  border-radius:999px;
  background:var(--ink);
  color:var(--paper);
  font:inherit;
  font-size:1rem;
  font-weight:500;
  cursor:pointer
}
.sub button:hover{background:var(--paper);color:var(--ink)}
.foot-nav ul{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:.4rem}
.foot-nav a{display:inline-block;padding:.7rem 1rem;border:1px solid var(--ink);border-radius:999px;border-bottom:1px solid var(--ink);font-size:1rem}
.foot-meta{margin:0;display:flex;flex-direction:column;align-items:flex-end;gap:.35rem}
.copy{margin:0;font-size:1rem}
.foot-meta .totop a{display:inline-block;padding:.7rem 0;font-size:1rem}
.foot-meta .totop a:hover{background:var(--ink);color:var(--paper);padding-inline:.5rem}

/* 动效 */
.js .reveal{opacity:0;transform:translateY(18px);transition:opacity .6s ease,transform .6s cubic-bezier(.2,.7,.3,1)}
.js .reveal.in{opacity:1;transform:none}

/* 窄屏 */
@media (max-width:900px){
  .top{flex-wrap:wrap;gap:.4rem;padding-top:.6rem;padding-bottom:.6rem}
  .wordmark{position:static;transform:none;order:-1;flex:1 1 auto}
  .call{order:0;margin-left:auto}
  .mainnav{order:1;flex:1 1 100%;padding-right:0;margin-top:.45rem}
  .navlist{display:flex;grid-template-columns:none;grid-template-rows:none;gap:.35rem;overflow-x:auto;padding-bottom:.2rem}
  .navitem{flex:0 0 auto}
  .navlist a{padding:.6rem .8rem}
  .stage{padding-top:1.25rem}
  .body,.rail{grid-column:1/-1}
  .hero{grid-template-columns:1fr;min-height:0}
  .hero-media,.hero-copy{grid-column:1/-1}
  .rail{position:static;margin-top:2rem}
  .foot{grid-template-columns:1fr;gap:1.6rem}
  .foot-meta{align-items:flex-start}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .js .reveal{opacity:1;transform:none;transition:none}
  .hero-img{transform:none}
}

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