:root{
  --ink:#000000;
  --paper:#ffffff;
  --line:rgba(0,0,0,.16);
  --mist:rgba(0,0,0,.05);
  --dim:rgba(0,0,0,.55);
  --edge:clamp(16px,4vw,56px);
  --sans:"Manrope",-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans SC","PingFang SC","Microsoft YaHei",sans-serif;
  --display:"Syne","Manrope",-apple-system,"Segoe UI","Noto Sans SC","PingFang SC",sans-serif;
}

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

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

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
}

body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  font-size:17px;
  font-weight:400;
  line-height:1.65;
  letter-spacing:.01em;
  overflow-wrap:break-word;
  -webkit-font-smoothing:antialiased;
}

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

/* 顶部细条与横向导航 */

.top{
  position:sticky;
  top:0;
  z-index:30;
  background:var(--paper);
  border-bottom:2px solid var(--ink);
}

.ticker{
  margin:0;
  padding:5px var(--edge);
  background:var(--ink);
  color:var(--paper);
  font-size:16px;
  line-height:1.5;
  letter-spacing:.22em;
  text-align:center;
  white-space:nowrap;
  overflow:hidden;
}

.bar{
  display:grid;
  grid-template-columns:1fr auto 1fr;
  align-items:center;
  gap:6px;
  padding:8px var(--edge);
}

.bnav ul{
  display:flex;
  flex-wrap:wrap;
  gap:2px;
  margin:0;
  padding:0;
  list-style:none;
}

.bnav-l ul{justify-content:flex-end}

.bnav a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 10px;
  font-size:16px;
  line-height:1.3;
  text-decoration:none;
  border-bottom:2px solid transparent;
  transition:background-color .18s ease,color .18s ease,border-color .18s ease;
}

.bnav a:hover,
.bnav a:focus-visible,
.bnav a[aria-current]{
  background:var(--ink);
  color:var(--paper);
  border-bottom-color:var(--ink);
}

.brand{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 14px;
  font-family:var(--display);
  font-size:clamp(18px,2.2vw,23px);
  font-weight:700;
  letter-spacing:-.02em;
  white-space:nowrap;
  text-decoration:none;
}

.brand:hover{background:var(--ink);color:var(--paper)}

/* 主视觉 */

.hero{
  display:flex;
  align-items:center;
  justify-content:center;
  gap:clamp(14px,3vw,44px);
  min-height:45vh;
  padding:clamp(26px,6vh,60px) var(--edge);
  border-bottom:2px solid var(--ink);
}

.hero h1{
  margin:0;
  max-width:15em;
  font-family:var(--display);
  font-size:clamp(30px,6vw,64px);
  font-weight:700;
  line-height:1.06;
  letter-spacing:-.03em;
}

.mark{
  flex:none;
  width:clamp(32px,5.6vw,60px);
  height:clamp(32px,5.6vw,60px);
  display:grid;
  grid-template-columns:1fr 1fr;
  grid-template-rows:1fr 1fr;
  gap:3px;
}

.mark i{display:block;background:var(--ink)}
.mark i:nth-child(2),
.mark i:nth-child(3){background:transparent;border:2px solid var(--ink)}

/* 栅格容器 */

.wrap{padding:0 var(--edge)}

.sheet{
  display:grid;
  grid-template-columns:repeat(12,1fr);
  gap:clamp(16px,2.2vw,36px);
  padding:clamp(26px,5vw,60px) 0 clamp(30px,6vw,70px);
  background-image:linear-gradient(90deg,var(--mist) 1px,transparent 1px);
  background-size:calc(100% / 12) 100%;
  background-repeat:repeat-y;
}

.prose{
  grid-column:1 / 10;
  min-width:0;
}

/* 正文 */

.prose > article{
  margin:0 0 clamp(24px,4vw,44px);
  padding-bottom:clamp(24px,4vw,44px);
  border-bottom:1px solid var(--line);
  scroll-margin-top:132px;
}

.prose > article:last-child{
  margin-bottom:0;
  padding-bottom:0;
  border-bottom:0;
}

.prose small{
  display:block;
  margin-bottom:.25em;
  font-size:16px;
  line-height:1.4;
  letter-spacing:.18em;
  color:var(--dim);
}

.prose h2{
  margin:0 0 .5em;
  font-family:var(--display);
  font-size:clamp(23px,3.2vw,36px);
  font-weight:700;
  line-height:1.14;
  letter-spacing:-.02em;
}

.prose h3{
  margin:1.4em 0 .4em;
  font-family:var(--display);
  font-size:clamp(19px,2.2vw,23px);
  font-weight:600;
  line-height:1.25;
}

.prose p{margin:0 0 1em;max-width:62ch}
.prose ul,.prose ol{margin:0 0 1em;padding-left:1.25em}
.prose li{margin:.35em 0;max-width:60ch}

.prose a{
  text-decoration:underline;
  text-decoration-thickness:1px;
  text-underline-offset:3px;
}

.prose a:hover{background:var(--ink);color:var(--paper);text-decoration:none}

.prose blockquote{
  margin:1.3em 0;
  padding:14px 18px;
  border:1px solid var(--line);
  border-left:3px solid var(--ink);
  border-radius:4px;
  background:rgba(255,255,255,.72);
  -webkit-backdrop-filter:blur(8px);
  backdrop-filter:blur(8px);
}

.prose blockquote p:last-child{margin-bottom:0}

.prose table{
  display:block;
  width:100%;
  margin:1em 0;
  border-collapse:collapse;
  font-size:16px;
  overflow-x:auto;
}

.prose th,.prose td{
  border:1px solid var(--line);
  padding:8px 10px;
  text-align:left;
  vertical-align:top;
}

.prose th{background:var(--mist);font-weight:600}

.prose code{
  padding:1px 5px;
  font-size:16px;
  background:var(--mist);
  border-radius:3px;
}

.prose img{margin:1em 0;border-radius:4px}
.prose figure{margin:1.2em 0}
.prose hr{border:0;border-top:1px solid var(--line);margin:1.6em 0}

/* 右侧索引 */

.side{
  grid-column:10 / -1;
  min-width:0;
  align-self:start;
  position:sticky;
  top:132px;
  padding:14px 14px 8px;
  border:1px solid var(--line);
  border-radius:4px;
  background:rgba(255,255,255,.72);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
}

.side small{
  display:block;
  font-size:16px;
  line-height:1.4;
  letter-spacing:.2em;
  color:var(--dim);
}

.side h2{
  margin:0 0 10px;
  font-family:var(--display);
  font-size:21px;
  font-weight:700;
  line-height:1.2;
  letter-spacing:-.01em;
}

.side ul{
  margin:0;
  padding:0;
  list-style:none;
  counter-reset:s;
}

.side li{counter-increment:s}

.side a{
  display:flex;
  align-items:center;
  gap:9px;
  min-height:44px;
  font-size:16px;
  line-height:1.3;
  text-decoration:none;
  border-bottom:1px solid var(--line);
  transition:background-color .18s ease,color .18s ease,padding-left .18s ease;
}

.side a::before{
  content:counter(s,decimal-leading-zero);
  font-family:var(--display);
  font-size:16px;
  line-height:1;
  color:var(--dim);
}

.side a:hover,
.side a[aria-current]{
  padding-left:8px;
  background:var(--ink);
  color:var(--paper);
}

.side a:hover::before,
.side a[aria-current]::before{color:rgba(255,255,255,.65)}

/* 页脚 */

.foot{
  display:grid;
  grid-template-columns:1.5fr 1fr 1fr auto;
  gap:clamp(16px,2vw,28px);
  padding:clamp(28px,5vw,56px) var(--edge) 18px;
  background:var(--ink);
  color:var(--paper);
}

.foot p{margin:0;font-size:16px;line-height:1.5}

.f-brand{
  font-family:var(--display);
  font-size:clamp(20px,3vw,30px);
  font-weight:700;
  line-height:1.18;
  letter-spacing:-.02em;
}

.f-links a{
  display:flex;
  align-items:center;
  min-height:44px;
  text-decoration:none;
  border-bottom:1px solid rgba(255,255,255,.22);
  transition:color .18s ease,border-color .18s ease;
}

.f-links a:hover{color:rgba(255,255,255,.6);border-bottom-color:rgba(255,255,255,.6)}

.f-copy{
  grid-column:1 / -1;
  display:block;
  padding-top:14px;
  border-top:1px solid rgba(255,255,255,.25);
  font-size:16px;
  color:rgba(255,255,255,.7);
}

/* 入场上浮 */

.js .prose > article{
  opacity:0;
  transform:translateY(14px);
  transition:opacity .55s cubic-bezier(.2,.7,.3,1),transform .55s cubic-bezier(.2,.7,.3,1);
  transition-delay:calc(var(--i,0) * 80ms);
}

.js .prose > article.is-in{opacity:1;transform:none}

@media (prefers-reduced-motion:reduce){
  .js .prose > article{opacity:1;transform:none;transition:none}
}

/* 中屏 */

@media (max-width:1080px){
  .bnav a{padding:0 8px}
  .f-links a{min-height:42px}
}

@media (max-width:880px){
  .sheet{grid-template-columns:1fr;background-image:none}
  .prose,.side{grid-column:1 / -1}
  .side{position:static;order:-1}
  .side ul{display:flex;flex-wrap:wrap;gap:2px}
  .side li{flex:1 1 auto}
  .side a{border-bottom:0;padding:0 10px}
  .side a::before{display:none}
  .foot{grid-template-columns:1fr 1fr}
  .f-brand{grid-column:1 / -1}
}

/* 小屏 */

@media (max-width:760px){
  .top{position:static}
  .bar{grid-template-columns:1fr;padding:10px var(--edge);gap:4px}
  .brand{order:-1;justify-content:center;padding:0}
  .bnav ul{justify-content:center}
  .bnav a{padding:0 12px}
  .hero{flex-direction:column;min-height:44vh;gap:16px;text-align:center}
  .hero h1{text-align:center;max-width:100%}
  .prose > article{scroll-margin-top:16px}
  .prose p,.prose li{max-width:100%}
}

@media (max-width:520px){
  body{font-size:16px}
  .foot{grid-template-columns:1fr;padding-bottom:16px}
  .f-copy{grid-column:1 / -1}
  .side ul{flex-direction:column}
  .side a{border-bottom:1px solid var(--line)}
}

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