@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:#000000;
  --paper:#ffffff;
  --muted:#3b3b3b;
  --rail:250px;
  --bar:46px;
  --radius:10px;
  --pad:clamp(1.15rem,4vw,3.25rem);
  --font:"Archivo","Space Grotesk",system-ui,-apple-system,"Segoe UI","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
}

html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}

body{
  margin:0;
  overflow-x:hidden;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font);
  font-size:17px;
  font-weight:400;
  line-height:1.72;
  letter-spacing:-.004em;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

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

/* 顶部细条 */
.ticker{
  position:fixed;top:0;left:0;right:0;height:var(--bar);z-index:70;
  display:flex;align-items:center;
  background:var(--ink);color:var(--paper);
  padding:0 var(--pad) 0 calc(var(--rail) + 1.5rem);
}
.ticker p{
  margin:0;font-size:15px;letter-spacing:.06em;line-height:1.4;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;
}

/* 左侧竖排导航 */
.rail{
  position:fixed;top:var(--bar);left:0;bottom:0;width:var(--rail);z-index:60;
  display:flex;flex-direction:column;gap:2.25rem;
  padding:1.6rem 1.35rem 2rem;
  background:var(--paper);border-right:1px solid var(--ink);
  overflow-y:auto;
}
.brand{
  display:inline-flex;align-items:center;gap:.6rem;min-height:40px;
  padding:.35rem 0;
  font-size:1.15rem;font-weight:700;letter-spacing:-.022em;
  text-decoration:none;
}
.brand::before{content:"";display:block;width:.7rem;height:.7rem;background:var(--ink)}
.rail nav ul{list-style:none;margin:0;padding:0;display:grid;gap:.5rem}
.rail nav a{
  display:flex;align-items:center;min-height:42px;
  padding:.5rem 1rem;
  border:1px solid var(--ink);border-radius:999px;
  font-size:15px;line-height:1.3;text-decoration:none;
  transition:background-color .22s ease,color .22s ease,transform .22s ease;
}
.rail nav a:hover,.rail nav a:focus-visible,.rail nav a.is-active{background:var(--ink);color:var(--paper)}
.rail nav a:hover{transform:translateX(2px)}

/* 主区 */
main{margin-left:var(--rail);padding-top:var(--bar)}
.wrap{max-width:1180px;margin:0 auto}

.hero{
  position:relative;min-height:70vh;
  display:grid;place-items:center;text-align:center;
  padding:clamp(2.5rem,8vh,5rem) var(--pad);
}
.hero h1{
  margin:0;max-width:17ch;
  font-size:clamp(2.1rem,6vw,4.9rem);
  font-weight:600;line-height:1.02;letter-spacing:-.035em;
  text-wrap:balance;
}
.hero::after{
  content:"";position:absolute;left:50%;bottom:1.25rem;
  width:1px;height:52px;background:var(--ink);opacity:.55;
  transform:translateX(-50%);
}

.sheet{
  border-top:1px solid var(--ink);
  padding:clamp(2rem,5vw,3.25rem) var(--pad) clamp(2.5rem,6vw,4.5rem);
}
.prose{max-width:74ch}
.sheet-title{
  margin:0 0 .5rem;
  font-size:clamp(1.5rem,3vw,2.1rem);
  font-weight:600;line-height:1.1;letter-spacing:-.03em;
}
.subtitle{
  margin:0 0 clamp(1.75rem,4vw,3rem);
  max-width:56ch;
  color:var(--muted);font-size:1.02rem;line-height:1.65;
}

.prose > section{
  padding-block:clamp(1.75rem,4vw,3rem);
  border-top:1px solid var(--ink);
  scroll-margin-top:calc(var(--bar) + 1.25rem);
}
.prose > section:first-of-type{border-top:0;padding-top:0}
.prose h2{
  margin:0 0 .85rem;
  font-size:clamp(1.35rem,2.6vw,1.9rem);
  font-weight:600;line-height:1.16;letter-spacing:-.025em;
}
.prose h3{margin:1.6rem 0 .6rem;font-size:1.12rem;font-weight:600;line-height:1.3}
.prose p{margin:0 0 1.1rem}
.prose ul,.prose ol{margin:0 0 1.2rem;padding-left:1.25rem}
.prose li{margin:.35rem 0}
.prose a{text-decoration:underline;text-underline-offset:.22em;text-decoration-thickness:1px}
.prose a:hover{background:var(--ink);color:var(--paper);text-decoration:none}
.prose blockquote{
  margin:1.5rem 0;padding:.2rem 0 .2rem 1.15rem;
  border-left:2px solid var(--ink);color:var(--muted);
}
.prose strong{font-weight:600}

/* 页脚 */
.foot{
  margin-left:var(--rail);
  border-top:1px solid var(--ink);
  padding:clamp(1.75rem,4vw,2.75rem) var(--pad) 0;
}
.foot-grid{
  display:grid;grid-template-columns:repeat(3,minmax(0,1fr));
  gap:2rem;max-width:1180px;margin:0 auto;
}
.foot dl{margin:0}
.foot dt{font-size:14px;letter-spacing:.14em;margin-bottom:.6rem}
.foot dd{margin:0 0 .35rem;font-size:15px;line-height:1.6;color:var(--muted)}
.foot dd a{
  display:inline-flex;align-items:center;min-height:40px;
  color:var(--ink);text-decoration:none;
}
.foot dd a:hover{text-decoration:underline;text-underline-offset:.2em}
.end{
  max-width:1180px;margin:clamp(1.5rem,4vw,2.5rem) auto 0;
  border-top:1px solid var(--ink);
  padding:1rem 0 2rem;
  font-size:14px;letter-spacing:.08em;
}

/* 入场 */
@media (prefers-reduced-motion: no-preference){
  html.js .prose > section{
    opacity:0;transform:translateY(12px);
    transition:opacity .5s ease,transform .5s ease;
    transition-delay:calc(var(--i,0) * 40ms);
  }
  html.js .prose > section.in{opacity:1;transform:none}
}

@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{transition-duration:.001ms !important;animation-duration:.001ms !important}
  .rail nav a:hover{transform:none}
}

/* 移动端 */
@media (max-width:880px){
  .ticker{padding-left:1rem}
  .ticker p{font-size:14px}
  .rail{
    top:var(--bar);bottom:auto;right:0;width:auto;
    flex-direction:column;gap:.4rem;
    padding:.55rem 1rem .4rem;
    border-right:0;border-bottom:1px solid var(--ink);
    overflow:visible;
  }
  .brand{font-size:1.05rem}
  .rail nav ul{
    display:flex;gap:.45rem;
    overflow-x:auto;padding-bottom:.3rem;
    scrollbar-width:none;
  }
  .rail nav ul::-webkit-scrollbar{display:none}
  .rail nav a{white-space:nowrap;min-height:42px;padding:.5rem .95rem}
  main{margin-left:0;padding-top:calc(var(--bar) + 118px)}
  .hero{min-height:52vh;padding-top:2rem;padding-bottom:3.5rem}
  .foot{margin-left:0}
  .foot-grid{grid-template-columns:1fr;gap:1.5rem}
  .prose > section{scroll-margin-top:calc(var(--bar) + 124px)}
}

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