@import url('https://fonts.googleapis.com/css2?family=Bodoni+Moda:wght@400;500;600;700&family=Jost:wght@300;400;500;600;700&display=swap');

:root{
  --ink:#1f1f1f;
  --paper:#ffffff;
  --mist:#f5f5f5;
  --line:#e6e6e6;
  --mute:#8a8a8a;
  --edge:max(16px, calc(50% - 590px));
  --shadow:0 4px 6px rgba(0,0,0,.05);
  --body:"Jost","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --head:"Bodoni Moda",Georgia,"Songti SC",serif;
}

*,*::before,*::after{box-sizing:border-box}

html{
  scroll-behavior:smooth;
  scroll-padding-top:104px;
  -webkit-text-size-adjust:100%;
}

body{
  margin:0;
  background:var(--mist);
  color:var(--ink);
  font-family:var(--body);
  font-size:17px;
  line-height:1.65;
  font-weight:400;
  letter-spacing:.005em;
}

h1,h2,h3{
  font-family:var(--head);
  font-weight:500;
  line-height:1.08;
  letter-spacing:-.015em;
}

a{color:inherit}
img{display:block;max-width:100%;height:auto}
p{margin:0}
section[id]{scroll-margin-top:104px}

/* 页头 */
.mast{
  display:flex;
  align-items:center;
  gap:clamp(10px,2.5vw,26px);
  padding:14px var(--edge);
  background:var(--paper);
  border-bottom:1px solid var(--line);
}

.mark{
  flex:0 0 auto;
  width:44px;
  height:44px;
  display:grid;
  place-items:center;
  overflow:hidden;
  border-radius:4px;
  background:var(--ink);
  color:#fff;
  text-decoration:none;
  font-family:var(--head);
  font-size:21px;
  line-height:1;
}
.mark img{width:100%;height:100%;object-fit:cover}

.mast .top{
  min-width:0;
  overflow-x:auto;
  scrollbar-width:none;
}
.mast .top::-webkit-scrollbar{display:none}

.mast .top p{
  display:flex;
  gap:2px;
  flex-wrap:nowrap;
}

.mast .top a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 12px;
  border-radius:4px;
  font-size:16px;
  text-decoration:none;
  white-space:nowrap;
  transition:background .2s ease,color .2s ease;
}
.mast .top a:hover,
.mast .top a:focus-visible{background:var(--mist)}

/* 粘性锚点条 */
.jumpbar{
  position:sticky;
  top:0;
  z-index:30;
  display:flex;
  gap:18px;
  padding:8px var(--edge);
  overflow-x:auto;
  background:rgba(255,255,255,.94);
  backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line);
  scrollbar-width:none;
}
.jumpbar::-webkit-scrollbar{display:none}

.jumpbar .grp{
  display:flex;
  align-items:center;
  gap:2px;
  flex:0 0 auto;
}

.jumpbar .grp > span{
  padding-right:8px;
  font-size:12px;
  letter-spacing:.2em;
  color:var(--mute);
  white-space:nowrap;
}

.jumpbar a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:0 10px;
  border-radius:4px;
  font-size:16px;
  text-decoration:none;
  white-space:nowrap;
  transition:background .2s ease;
}
.jumpbar a:hover,
.jumpbar a:focus-visible{background:var(--mist)}

/* 主区 */
main{padding:0 var(--edge)}

.hero{
  min-height:45vh;
  display:flex;
  flex-direction:column;
  align-items:flex-start;
  justify-content:center;
  gap:20px;
  padding:clamp(34px,7vw,74px) 0 clamp(26px,5vw,50px);
}

.badge{
  background:var(--ink);
  color:#fff;
  padding:7px 14px;
  border-radius:4px;
  font-size:14px;
  letter-spacing:.08em;
}

.hero h1{
  margin:0;
  max-width:16ch;
  font-size:clamp(2.5rem,9vw,5.4rem);
  line-height:1.02;
}

.sheet{
  display:grid;
  grid-template-columns:minmax(0,1fr) 306px;
  align-items:start;
  gap:20px;
  padding-bottom:clamp(34px,6vw,64px);
}

/* 正文 */
.prose{
  min-width:0;
  padding:clamp(18px,4vw,44px);
  background:var(--paper);
  border-radius:4px;
  box-shadow:var(--shadow);
}

.prose > section + section{
  margin-top:clamp(26px,4vw,44px);
  padding-top:clamp(26px,4vw,44px);
  border-top:1px solid var(--line);
}

.prose h2{
  margin:0 0 .55em;
  font-size:clamp(1.5rem,3.2vw,2.05rem);
}
.prose h3{
  margin:1.4em 0 .45em;
  font-size:clamp(1.18rem,2.2vw,1.42rem);
}
.prose p{margin:0 0 1em}
.prose ul,.prose ol{margin:0 0 1em;padding-left:1.25em}
.prose li{margin:.3em 0}
.prose a{
  text-decoration:underline;
  text-underline-offset:3px;
  text-decoration-color:#bdbdbd;
  text-decoration-thickness:1px;
}
.prose a:hover{text-decoration-color:var(--ink)}
.prose blockquote{
  margin:1.2em 0;
  padding:14px 18px;
  background:var(--mist);
  border-left:3px solid var(--ink);
  border-radius:4px;
}
.prose blockquote p:last-child{margin-bottom:0}
.prose figure{margin:1.2em 0}
.prose figcaption{margin-top:8px;font-size:15px;color:var(--mute)}
.prose img{border-radius:4px;margin:1.2em 0}
.prose table{width:100%;border-collapse:collapse;font-size:16px}
.prose th,.prose td{padding:8px;text-align:left;border-bottom:1px solid var(--line)}
.prose hr{margin:1.6em 0;border:0;border-top:1px solid var(--line)}

/* 侧栏 */
.rail{
  position:sticky;
  top:96px;
  display:grid;
  align-content:start;
  gap:16px;
}

.rail-card{
  padding:18px;
  background:var(--paper);
  border-radius:4px;
  box-shadow:var(--shadow);
  transition:transform .25s ease;
}
.rail-card:hover{transform:scale(1.015)}

.eyebrow{
  display:block;
  font-size:12px;
  letter-spacing:.22em;
  color:var(--mute);
}

.rail-card h2{
  margin:6px 0 10px;
  font-size:1.15rem;
}

.rail-list{display:grid;gap:2px}
.rail-list a{
  display:block;
  padding:9px 6px;
  border-bottom:1px solid var(--mist);
  font-size:16px;
  text-decoration:none;
  transition:background .2s ease,padding-left .2s ease;
}
.rail-list a:hover,
.rail-list a:focus-visible{background:var(--mist);padding-left:14px}

.rot{
  min-height:1.4em;
  margin-top:6px;
  font-family:var(--head);
  font-size:1.3rem;
  line-height:1.3;
  transition:opacity .3s ease;
}
.rot.is-out{opacity:0}

/* 页脚 */
.foot{
  display:grid;
  grid-template-columns:1fr auto;
  align-items:start;
  gap:12px 24px;
  padding:clamp(32px,6vw,58px) var(--edge) 30px;
  background:var(--paper);
  border-top:1px solid var(--line);
}

.foot-cta{
  grid-column:1 / -1;
  margin:0 0 10px;
  padding-bottom:18px;
  border-bottom:1px solid var(--line);
  font-family:var(--head);
  font-size:clamp(2.1rem,7vw,4rem);
  line-height:1.02;
  letter-spacing:-.02em;
}

.foot-about{color:var(--mute)}

.foot-links{
  display:flex;
  flex-wrap:wrap;
  justify-content:flex-end;
  gap:2px 18px;
}
.foot-links a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  font-size:16px;
  text-decoration:none;
}
.foot-links a:hover{text-decoration:underline}

.foot-copy{font-size:14px;color:var(--mute)}

.foot-top{text-align:right}
.foot-top a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:0 2px;
  font-size:16px;
  text-decoration:none;
}
.foot-top a:hover{text-decoration:underline}

/* 动效 */
.reveal{
  opacity:0;
  transform:translateY(10px);
  transition:opacity .55s ease,transform .55s ease;
}
.reveal.in{opacity:1;transform:none}

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

@media (max-width:900px){
  .sheet{grid-template-columns:1fr}
  .rail{position:static;grid-template-columns:1fr 1fr;order:2}
  .foot{grid-template-columns:1fr}
  .foot-links{justify-content:flex-start}
  .foot-top{text-align:left}
}

@media (max-width:560px){
  .rail{grid-template-columns:1fr}
  .hero{min-height:44vh}
  .foot-links{gap:0 14px}
}

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