@import url('https://fonts.googleapis.com/css2?family=Abril+Fatface&family=Merriweather:wght@300;400;700&display=swap');

:root{
  --paper:#fdfbf7;
  --wash:#f5f5f5;
  --ink:#1a1a1a;
  --rule:#e0e0e0;
  --mute:#57534e;
  --rail:220px;
  --side:258px;
}

*,*::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:"Merriweather",Georgia,"Songti SC","Noto Serif SC",serif;
  font-size:17px;
  line-height:1.75;
  font-weight:400;
  transition:none;
  overflow-x:hidden;
}

body::before{
  content:"";
  position:fixed;
  inset:0;
  z-index:900;
  pointer-events:none;
  opacity:.32;
  mix-blend-mode:multiply;
  background-image:url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='140' height='140'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.8' numOctaves='2' stitchTiles='stitch'/></filter><rect width='140' height='140' filter='url(%23n)' opacity='0.42'/></svg>");
}

a{color:var(--ink);text-decoration:underline;text-underline-offset:3px;text-decoration-thickness:1px;transition:none}
a:hover{text-decoration-thickness:3px}

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

.sr{
  position:absolute;
  width:1px;height:1px;
  padding:0;margin:-1px;
  overflow:hidden;
  clip:rect(0 0 0 0);
  white-space:nowrap;
  border:0;
}

.skip{
  position:absolute;
  top:0;left:0;
  padding:10px 16px;
  background:var(--ink);
  color:var(--paper);
  z-index:1000;
  transform:translateY(-140%);
}
.skip:focus{transform:none}

/* ---------- 左栏 ---------- */
.shell{
  display:grid;
  grid-template-columns:var(--rail) minmax(0,1fr);
  min-height:100vh;
}

.rail{
  position:fixed;
  inset:0 auto 0 0;
  width:var(--rail);
  z-index:20;
  display:flex;
  flex-direction:column;
  gap:22px;
  padding:26px 18px 22px;
  background:var(--wash);
  border-right:1px solid var(--rule);
  overflow-y:auto;
}

.brand{
  display:inline-flex;
  align-items:center;
  gap:9px;
  font-family:"Abril Fatface","Merriweather",Georgia,serif;
  font-size:23px;
  line-height:1.2;
  letter-spacing:.02em;
  text-decoration:none;
  padding:6px 0 16px;
  border-bottom:3px solid var(--ink);
}
.brand-img{
  display:block;
  width:34px;height:34px;
  border:1px solid var(--ink);
  border-radius:50%;
}

.rail-list{
  list-style:none;
  margin:0;
  padding:0;
  display:flex;
  flex-direction:column;
}
.rail-list li{margin:0}
.rail-list a{
  display:block;
  padding:12px 8px;
  font-size:16px;
  line-height:1.5;
  text-decoration:none;
  border-radius:18px;
  border:1px solid transparent;
  word-break:break-word;
}
.rail-list a:hover,
.rail-list a:focus-visible{
  background:var(--paper);
  border-color:var(--ink);
}

.rail-find{
  margin-top:auto;
  display:flex;
  flex-direction:column;
  gap:10px;
  padding-top:14px;
  border-top:1px solid var(--rule);
}
.rail-find input{
  width:100%;
  min-height:42px;
  padding:9px 12px;
  font:inherit;
  font-size:16px;
  color:var(--ink);
  background:var(--paper);
  border:1px solid var(--rule);
  border-radius:18px;
  transition:none;
}
.rail-find input:focus{
  outline:none;
  border-color:var(--ink);
}
.rail-top{
  display:block;
  padding:10px 8px;
  font-size:16px;
  text-decoration:none;
  text-align:center;
  border:1px solid var(--ink);
  border-radius:18px;
  background:var(--ink);
  color:var(--paper);
}

/* ---------- 内容区 ---------- */
.stage{
  grid-column:2;
  display:grid;
  grid-template-columns:minmax(0,1fr) var(--side);
  align-items:start;
  gap:46px;
  padding:0 34px 64px 42px;
}

main{min-width:0}

article{
  max-width:64ch;
}

.hero{
  display:flex;
  align-items:center;
  gap:26px;
  min-height:45vh;
  padding:34px 0 34px;
  border-bottom:3px solid var(--ink);
}

.hero-copy{min-width:0}
.hero h1{
  font-family:"Abril Fatface","Merriweather",Georgia,serif;
  font-size:clamp(28px,4.6vw,54px);
  font-weight:400;
  line-height:1.12;
  letter-spacing:.005em;
  margin:0;
}
.hero-lede{
  margin:16px 0 0;
  font-size:16px;
  line-height:1.7;
  color:var(--mute);
}

.hero-mark{
  flex:0 0 auto;
  margin:0;
  padding:13px;
  color:var(--ink);
  background:rgba(255,255,255,.55);
  border:1px solid rgba(26,26,26,.16);
  border-radius:18px;
  backdrop-filter:blur(7px) saturate(1.15);
  -webkit-backdrop-filter:blur(7px) saturate(1.15);
}
.hero-mark svg{display:block;width:56px;height:56px}

article > section{
  padding:44px 0;
  border-bottom:1px solid var(--rule);
  scroll-margin-top:26px;
}
article > section:last-child{border-bottom:0}

article h2{
  font-size:clamp(21px,2.4vw,29px);
  font-weight:700;
  line-height:1.28;
  letter-spacing:-.01em;
  margin:0 0 16px;
}
article h3{
  font-size:19px;
  font-weight:700;
  line-height:1.4;
  margin:30px 0 12px;
}
article h2:first-child,
article h3:first-child{margin-top:0}

article small{
  display:block;
  font-size:13.5px;
  line-height:1.5;
  letter-spacing:.24em;
  color:var(--mute);
  margin-bottom:7px;
}

article p{margin:0 0 18px}
article ul,
article ol{margin:0 0 18px;padding-left:1.35em}
article li{margin:0 0 7px}
article li::marker{color:var(--ink)}

article a{
  background:linear-gradient(transparent 68%,rgba(26,26,26,.14) 68%);
  text-decoration-thickness:1px;
}
article a:hover{background:var(--ink);color:var(--paper);text-decoration:none}

article blockquote{
  margin:26px 0;
  padding:16px 20px;
  border-left:4px solid var(--ink);
  background:rgba(255,255,255,.55);
  border-radius:0 18px 18px 0;
  backdrop-filter:blur(6px);
  -webkit-backdrop-filter:blur(6px);
}
article blockquote p:last-child{margin-bottom:0}

article figure{margin:26px 0}
article figcaption{
  margin-top:9px;
  font-size:13.5px;
  color:var(--mute);
}

article table{
  width:100%;
  border-collapse:collapse;
  margin:0 0 20px;
  font-size:16px;
}
article th,
article td{
  border:1px solid var(--rule);
  padding:10px 12px;
  text-align:left;
  vertical-align:top;
}
article th{background:var(--wash)}

article code{
  font-family:ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  font-size:.92em;
  padding:1px 5px;
  border:1px solid var(--rule);
  border-radius:5px;
  background:var(--wash);
}
article pre{
  overflow-x:auto;
  padding:16px;
  margin:0 0 20px;
  border:1px solid var(--rule);
  border-radius:18px;
  background:var(--wash);
}
article pre code{border:0;background:none;padding:0}

article hr{
  border:0;
  border-top:1px solid var(--rule);
  margin:30px 0;
}

/* ---------- 右栏 ---------- */
.side{
  position:sticky;
  top:30px;
  margin:44px 0 0;
  padding:16px 16px 8px;
  background:rgba(255,255,255,.6);
  border:1px solid rgba(26,26,26,.14);
  border-radius:18px;
  backdrop-filter:blur(9px) saturate(1.15);
  -webkit-backdrop-filter:blur(9px) saturate(1.15);
}
.side small{
  display:block;
  font-size:13px;
  letter-spacing:.24em;
  color:var(--mute);
  margin:0 0 5px;
}
.side h2{
  font-family:"Abril Fatface","Merriweather",Georgia,serif;
  font-size:21px;
  font-weight:400;
  line-height:1.25;
  margin:0 0 12px;
  padding-bottom:11px;
  border-bottom:1px solid var(--rule);
}
.side-list{
  list-style:none;
  margin:0;
  padding:0;
}
.side-list li{margin:0}
.side-list li.is-off{display:none}
.side-list a{
  display:block;
  padding:10px 4px;
  font-size:16px;
  line-height:1.5;
  text-decoration:none;
  border-bottom:1px dotted var(--rule);
}
.side-list li:last-child a{border-bottom:0}
.side-list a:hover{
  background:var(--ink);
  color:var(--paper);
}

/* ---------- 页脚 ---------- */
footer{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:12px 30px;
  max-width:1000px;
  padding:40px 34px 34px calc(var(--rail) + 42px);
  background:var(--wash);
  border-top:3px solid var(--ink);
}

footer dl{
  margin:0;
  min-width:0;
}
footer dt{
  font-size:13px;
  letter-spacing:.24em;
  color:var(--mute);
  margin:0 0 10px;
}
footer dd{
  margin:0;
}
footer dd a{
  display:inline-block;
  padding:9px 0;
  font-size:16px;
  line-height:1.5;
  text-decoration:none;
}
footer dd a:hover{text-decoration:underline;text-decoration-thickness:3px}

.colophon{
  grid-column:1 / -1;
  margin:18px 0 0;
  padding-top:16px;
  border-top:1px solid var(--rule);
  font-size:15px;
  color:var(--mute);
}

/* ---------- 揭示 ---------- */
.js article > div,
.js .side,
.js footer{opacity:0}
.js .is-in{opacity:1}

/* ---------- 窄屏 ---------- */
@media (max-width:900px){
  :root{--rail:88px}
  .rail{
    padding:18px 8px 16px;
    gap:16px;
  }
  .brand{
    font-size:17px;
    padding:4px 2px 12px;
    gap:0;
    justify-content:center;
    text-align:center;
  }
  .brand-img{width:28px;height:28px}
  .rail-list a{
    padding:12px 4px;
    font-size:16px;
    text-align:center;
    border-radius:12px;
  }
  .rail-find input{
    padding:8px 6px;
    text-align:center;
    border-radius:12px;
  }
  .rail-top{
    padding:10px 2px;
    font-size:15px;
    border-radius:12px;
  }
  .stage{
    grid-template-columns:minmax(0,1fr);
    gap:0;
    padding:0 14px 48px;
  }
  .side{
    grid-column:1;
    position:static;
    margin-top:26px;
  }
  .hero{
    gap:13px;
    min-height:0;
    padding:26px 0;
    align-items:flex-start;
  }
  .hero-mark{padding:8px;border-radius:14px}
  .hero-mark svg{width:40px;height:40px}
  .hero-lede{font-size:16px;margin-top:12px}
  article > div{padding:32px 0}
  footer{
    grid-template-columns:repeat(3,minmax(0,1fr));
    gap:10px 12px;
    padding:30px 14px 28px calc(var(--rail) + 14px);
  }
  footer dd a{font-size:15px;padding:10px 0}
}

@media (max-width:420px){
  :root{--rail:82px}
  body{font-size:16px}
  .rail-list a{font-size:15px;padding:13px 2px}
  .rail-top{font-size:14px}
  footer dd a{font-size:15px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .js article > div,
  .js .side,
  .js footer{opacity:1}
}

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