:root{
  --ink:#000;
  --paper:#fff;
  --mono:"Space Mono",ui-monospace,SFMono-Regular,Menlo,monospace;
  --display:"Syncopate",system-ui,-apple-system,"PingFang SC","Microsoft YaHei",sans-serif;
  --text:system-ui,-apple-system,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --bd:1px solid #000;
  --r:4px;
  --wrap:1200px;
  --pad:24px;
}

*,*::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-family:var(--text);
  font-size:17px;
  line-height:1.7;
  overflow-x:hidden;
}

h1,h2,h3{
  margin:0;
  font-family:var(--display);
  font-weight:700;
  line-height:1.08;
  letter-spacing:-.01em;
}

p{margin:0 0 16px}

a{color:inherit}
a:focus-visible{outline:2px solid currentColor;outline-offset:3px}

img{display:block;max-width:100%;height:auto}

/* ---------- 页头 ---------- */
.site-head{
  position:sticky;
  top:0;
  z-index:30;
  background:var(--paper);
  border-bottom:var(--bd);
}

.head-top{
  max-width:var(--wrap);
  margin:0 auto;
  padding:12px var(--pad);
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
}

.brand{
  display:inline-flex;
  align-items:center;
  gap:10px;
  min-height:40px;
  font-family:var(--display);
  font-size:16px;
  letter-spacing:.14em;
  text-decoration:none;
}

.brand img{width:auto;height:26px}

.head-cta{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:10px 18px;
  background:var(--ink);
  color:var(--paper);
  border:1px solid var(--ink);
  border-radius:var(--r);
  font-family:var(--mono);
  font-size:16px;
  text-decoration:none;
  transition:background .22s ease,color .22s ease;
}
.head-cta:hover{background:var(--paper);color:var(--ink)}

.head-nav{
  max-width:var(--wrap);
  margin:0 auto;
  padding:0 var(--pad);
  border-top:var(--bd);
}

.head-nav nav{
  overflow-x:auto;
  scrollbar-width:thin;
}

.head-nav nav p{
  display:flex;
  flex-wrap:nowrap;
  align-items:stretch;
  gap:0;
  margin:0;
}

.head-nav nav a{
  display:inline-flex;
  align-items:center;
  min-height:46px;
  padding:10px 14px 10px 0;
  margin-right:14px;
  font-family:var(--mono);
  font-size:16px;
  white-space:nowrap;
  text-decoration:none;
  border-bottom:2px solid transparent;
  transition:border-color .22s ease,opacity .22s ease;
}
.head-nav nav a:hover{border-bottom-color:var(--ink)}

/* ---------- 主体 ---------- */
main{
  max-width:var(--wrap);
  margin:0 auto;
  padding:0 var(--pad);
}

.hero{
  position:relative;
  min-height:45vh;
  display:flex;
  flex-direction:column;
  justify-content:flex-end;
  gap:28px;
  padding:64px 0 36px;
  border-bottom:var(--bd);
  text-align:right;
}

.hero h1{
  font-size:clamp(2.2rem,7vw,5rem);
  word-break:break-word;
  letter-spacing:-.02em;
}

.badge{
  position:absolute;
  left:0;
  top:28px;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  width:44px;
  height:44px;
  border:var(--bd);
  border-radius:var(--r);
  font-family:var(--mono);
  font-size:16px;
  background:var(--ink);
  color:var(--paper);
}

.hero-fig{
  align-self:flex-start;
  margin:0;
  display:grid;
  grid-template-columns:repeat(4,1fr);
  gap:8px;
  width:min(240px,100%);
}

.hero-fig span{
  display:block;
  height:34px;
  border:var(--bd);
  border-radius:2px;
}
.hero-fig span:nth-child(odd){background:var(--ink)}

/* ---------- 正文区 ---------- */
.doc{
  display:grid;
  grid-template-columns:minmax(0,1fr) 268px;
  gap:0 48px;
  padding:56px 0 72px;
}

.doc > h2{
  grid-column:1 / -1;
  font-size:clamp(1.5rem,3.4vw,2.3rem);
  letter-spacing:.02em;
}

.doc > .subtitle{
  grid-column:1 / -1;
  margin:14px 0 40px;
  padding-left:14px;
  border-left:3px solid var(--ink);
  font-family:var(--mono);
  font-size:16px;
  max-width:62ch;
}

.doc > .prose{
  grid-column:1;
  grid-row:3;
  min-width:0;
}

.doc > .rail{
  grid-column:2;
  grid-row:3;
}

.prose section{
  padding:34px 0;
  border-top:var(--bd);
  scroll-margin-top:150px;
}
.prose section:first-child{border-top:0;padding-top:0}

.prose h2{
  font-size:clamp(1.35rem,2.6vw,1.9rem);
  margin:0 0 18px;
}

.prose h3{
  font-size:17px;
  margin:24px 0 12px;
  letter-spacing:.02em;
}

.prose p,.prose ul,.prose ol,.prose blockquote{
  max-width:66ch;
}

.prose ul,.prose ol{padding-left:22px;margin:0 0 18px}
.prose li{margin:0 0 10px}
.prose li::marker{font-family:var(--mono)}

.prose a{
  text-decoration:underline;
  text-underline-offset:3px;
  text-decoration-thickness:1px;
  transition:opacity .2s ease;
}
.prose a:hover{opacity:.6}

.prose blockquote{
  margin:0 0 18px;
  padding:2px 0 2px 16px;
  border-left:3px solid var(--ink);
}

.prose figure{
  margin:0 0 18px;
  padding:10px;
  border:var(--bd);
  border-radius:var(--r);
}

.prose figcaption{
  margin-top:8px;
  font-family:var(--mono);
  font-size:16px;
}

.prose strong{font-weight:700}

/* ---------- 侧栏 ---------- */
.rail{
  position:sticky;
  top:150px;
  align-self:start;
  border:var(--bd);
  border-radius:var(--r);
  padding:16px;
}

.rail h3{
  font-family:var(--mono);
  font-size:16px;
  font-weight:700;
  letter-spacing:.08em;
  margin:0 0 12px;
  padding-bottom:10px;
  border-bottom:var(--bd);
}

.rail ol{
  list-style:none;
  margin:0;
  padding:0;
  counter-reset:rail;
}

.rail li{counter-increment:rail}

.rail a{
  display:flex;
  align-items:center;
  gap:10px;
  min-height:44px;
  padding:8px 0;
  font-size:16px;
  text-decoration:none;
  border-bottom:1px solid #00000022;
  transition:padding-left .22s ease;
}

.rail li:last-child a{border-bottom:0}
.rail a:hover{padding-left:6px}

.rail a::before{
  content:counter(rail,decimal-leading-zero);
  font-family:var(--mono);
  font-size:16px;
  opacity:.55;
}

/* ---------- 页脚 ---------- */
.foot{
  margin-top:0;
  background:var(--ink);
  color:var(--paper);
  border-top:var(--bd);
}

.cta{
  max-width:var(--wrap);
  margin:0 auto;
  padding:64px var(--pad);
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:24px;
  border-bottom:1px solid #ffffff55;
}

.cta p{
  margin:0;
  font-family:var(--display);
  font-size:clamp(1.6rem,5vw,3.2rem);
  line-height:1.08;
  word-break:break-word;
}

.btn{
  display:inline-flex;
  align-items:center;
  min-height:48px;
  padding:12px 26px;
  border:1px solid var(--paper);
  border-radius:var(--r);
  color:var(--paper);
  font-family:var(--mono);
  font-size:16px;
  text-decoration:none;
  transition:background .22s ease,color .22s ease;
}
.btn:hover{background:var(--paper);color:var(--ink)}

.cols{
  max-width:var(--wrap);
  margin:0 auto;
  padding:44px var(--pad);
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:32px;
}

.cols dl{margin:0}

.cols dt{
  font-family:var(--mono);
  font-size:16px;
  letter-spacing:.1em;
  margin-bottom:10px;
  padding-bottom:10px;
  border-bottom:1px solid #ffffff55;
}

.cols dd{margin:0}

.cols dd a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:6px 0;
  font-size:16px;
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:border-color .22s ease;
}
.cols dd a:hover{border-bottom-color:var(--paper)}

.bottom{
  max-width:var(--wrap);
  margin:0 auto;
  padding:20px var(--pad) 44px;
  text-align:center;
  border-top:1px solid #ffffff55;
}

.bottom p{
  margin:0;
  font-family:var(--mono);
  font-size:16px;
}

/* ---------- 动效 ---------- */
.js .reveal{
  opacity:0;
  transform:translateY(14px);
  transition:opacity .5s ease,transform .5s ease;
}
.js .reveal.in{opacity:1;transform:none}

.js .rail li{
  opacity:0;
  transform:translateY(8px);
  transition:opacity .35s ease,transform .35s ease;
}
.js .rail.in li{opacity:1;transform:none}
.js .rail.in li:nth-child(2){transition-delay:.05s}
.js .rail.in li:nth-child(3){transition-delay:.1s}
.js .rail.in li:nth-child(4){transition-delay:.15s}
.js .rail.in li:nth-child(5){transition-delay:.2s}
.js .rail.in li:nth-child(6){transition-delay:.25s}
.js .rail.in li:nth-child(7){transition-delay:.3s}

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

/* ---------- 窄屏 ---------- */
@media (max-width:880px){
  :root{--pad:18px}

  .head-top{padding:10px var(--pad)}
  .head-cta{padding:10px 14px}

  .hero{
    min-height:0;
    padding:56px 0 30px;
    gap:22px;
  }
  .hero h1{font-size:clamp(1.9rem,8vw,2.8rem)}
  .badge{top:18px;width:40px;height:40px}

  .doc{
    grid-template-columns:minmax(0,1fr);
    gap:0;
    padding:40px 0 56px;
  }
  .doc > .subtitle{margin-bottom:32px}
  .doc > .prose,
  .doc > .rail{
    grid-column:1;
    grid-row:auto;
  }
  .doc > .rail{
    position:static;
    margin-top:32px;
  }

  .prose section{scroll-margin-top:170px}

  .cta{
    flex-direction:column;
    align-items:flex-start;
    padding:44px var(--pad);
  }

  .cols{
    grid-template-columns:minmax(0,1fr);
    gap:20px;
    padding:32px var(--pad);
  }
}

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