@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:ital,wght@0,400;0,500;0,700;1,400&display=swap');

:root{
  --ink:#000000;
  --paper:#ffffff;
  --hair:#e3e3e3;
  --muted:#5c5c5c;
  --u:8px;
  --pad:clamp(16px,4vw,48px);
  --ff:"Plus Jakarta Sans","Helvetica Neue",Helvetica,Arial,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
}

*,*::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(--ff);
  font-size:16px;
  line-height:1.65;
  font-weight:400;
}

img{display:block;max-width:100%}
a{color:inherit}
p{margin:0 0 1em}
::selection{background:#000;color:#fff}

a:focus-visible,button:focus-visible{outline:2px solid #000;outline-offset:3px}
.foot a:focus-visible{outline-color:#fff}

.skip{
  position:absolute;
  left:8px;
  top:-72px;
  z-index:90;
  background:#000;
  color:#fff;
  padding:12px 16px;
  border-radius:4px;
  text-decoration:none;
  transition:top .18s ease;
}
.skip:focus{top:8px}

/* ---------- 顶栏 ---------- */
.masthead{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  padding:16px var(--pad) 12px;
}

.mark{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  min-width:48px;
  min-height:48px;
  padding:0 10px;
  border:1px solid var(--ink);
  border-radius:4px;
  background:#fff;
  text-decoration:none;
}
.mark img{width:26px;height:26px;object-fit:contain}
.mark-txt{font-size:14px;font-weight:700;letter-spacing:.12em}

.burger{
  min-height:48px;
  padding:0 20px;
  border:1px solid var(--ink);
  border-radius:4px;
  background:#000;
  color:#fff;
  font-family:inherit;
  font-size:16px;
  font-weight:500;
  letter-spacing:.12em;
  cursor:pointer;
}
.burger[aria-expanded="true"]{background:#fff;color:#000}

/* ---------- 粘性锚点条 ---------- */
.anchors{
  position:sticky;
  top:0;
  z-index:50;
  background:#fff;
  border-top:1px solid var(--ink);
  border-bottom:1px solid var(--ink);
}
.anchors ol{
  display:flex;
  margin:0;
  padding:0;
  list-style:none;
  overflow-x:auto;
  scrollbar-width:none;
}
.anchors ol::-webkit-scrollbar{display:none}
.anchors li{flex:0 0 auto}
.anchors a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 14px;
  font-size:16px;
  text-decoration:none;
  white-space:nowrap;
  border-right:1px solid var(--hair);
}
.anchors a:hover{background:#000;color:#fff}

/* ---------- 全屏遮罩菜单 ---------- */
.overlay{
  position:fixed;
  inset:0;
  z-index:70;
  display:grid;
  place-items:center;
  padding:72px var(--pad);
  overflow-y:auto;
  background:#000;
  color:#fff;
  opacity:0;
  visibility:hidden;
  transition:opacity .28s ease,visibility .28s ease;
}
body.menu-open .overlay{opacity:1;visibility:visible}
body.menu-open{overflow:hidden}

.overlay ol{
  width:min(100%,640px);
  margin:0;
  padding:0;
  list-style:none;
  counter-reset:m;
}
.overlay li{
  counter-increment:m;
  border-bottom:1px solid #333;
}
.overlay li:first-child{border-top:1px solid #333}
.overlay a{
  display:flex;
  align-items:center;
  gap:16px;
  min-height:56px;
  padding:4px 8px;
  color:#fff;
  text-decoration:none;
  font-size:clamp(18px,4.6vw,28px);
  font-weight:700;
  letter-spacing:-.01em;
}
.overlay a::before{
  content:counter(m,decimal-leading-zero);
  min-width:26px;
  font-size:12px;
  font-weight:500;
  letter-spacing:.14em;
  color:#9a9a9a;
}
.overlay a:hover{background:#fff;color:#000}

/* ---------- 主体网格 ---------- */
main{
  display:grid;
  grid-template-columns:minmax(0,1fr) 17rem;
  column-gap:clamp(24px,4vw,56px);
  align-items:start;
  padding:0 var(--pad) 64px;
}
main > article{min-width:0}

.hero{
  grid-column:1 / -1;
  display:grid;
  grid-template-columns:minmax(0,1fr) auto;
  gap:clamp(16px,3vw,32px);
  align-items:center;
  min-height:45vh;
  padding:clamp(24px,5vw,48px) 0;
  border-bottom:1px solid var(--ink);
  background-image:radial-gradient(#dcdcdc 1px,transparent 1px);
  background-size:16px 16px;
  background-position:0 4px;
}
.hero h1{
  margin:0;
  max-width:20ch;
  font-size:clamp(1.65rem,7.4vw,3.9rem);
  line-height:1.04;
  letter-spacing:-.035em;
  font-weight:700;
  overflow-wrap:break-word;
}
.hero-fig{
  margin:0;
  width:clamp(72px,16vw,160px);
  aspect-ratio:1;
  display:grid;
  place-items:center;
  overflow:hidden;
  border:1px solid var(--ink);
  border-radius:4px;
  background:#fff;
}
.hero-fig img{width:100%;height:100%;object-fit:cover}
.hero-mono{
  font-size:clamp(28px,7vw,64px);
  font-weight:700;
  letter-spacing:-.04em;
  color:#000;
}

/* ---------- 右侧栏 ---------- */
.rail{
  grid-column:2;
  grid-row:2;
  align-self:start;
  position:sticky;
  top:64px;
  padding:clamp(24px,4vw,40px) 0;
}
.rail-in{border-top:2px solid var(--ink);padding-top:16px}
.rail-title{
  margin:0 0 .35em;
  font-size:16px;
  font-weight:700;
  letter-spacing:.18em;
}
.rail .subtitle{
  margin:0 0 18px;
  color:var(--muted);
  font-size:16px;
  line-height:1.55;
}
.toc{margin:0;padding:0;list-style:none;counter-reset:t}
.toc li{counter-increment:t}
.toc a{
  display:flex;
  align-items:center;
  gap:10px;
  min-height:40px;
  padding:2px 0;
  font-size:16px;
  text-decoration:none;
  border-bottom:1px solid var(--hair);
}
.toc a::before{
  content:counter(t,decimal-leading-zero);
  font-size:12px;
  letter-spacing:.1em;
  color:#8f8f8f;
}
.toc a:hover{background:#000;color:#fff}

/* ---------- 正文各节 ---------- */
main > article:not(.hero):not(.rail){
  grid-column:1;
  padding:clamp(32px,5vw,56px) 0;
  border-bottom:1px solid var(--ink);
  scroll-margin-top:64px;
}

main > article:not(.hero):not(.rail) > h2{
  margin:0 0 .45em;
  font-size:clamp(1.4rem,3.6vw,2.1rem);
  line-height:1.16;
  letter-spacing:-.025em;
  font-weight:700;
  max-width:24ch;
}
main > article:not(.hero):not(.rail) > h2 + p{
  color:var(--muted);
  font-size:17px;
}
main h3{
  margin:1.7em 0 .4em;
  font-size:18px;
  line-height:1.35;
  letter-spacing:-.01em;
  font-weight:700;
}
main p{max-width:68ch;font-size:17px;line-height:1.7}
main ul,main ol{padding-left:1.25em;max-width:68ch}
main li{margin:.35em 0;font-size:17px;line-height:1.7}
main figure{margin:1.4em 0}
main figcaption{font-size:16px;color:var(--muted);margin-top:.5em}
main blockquote{
  margin:1.4em 0;
  padding:8px 0 8px 20px;
  border-left:3px solid var(--ink);
  font-size:17px;
}
main a{text-decoration:underline;text-underline-offset:3px}
main a:hover{background:#000;color:#fff}
main img{border-radius:4px}
main strong{font-weight:700}

/* ---------- 页脚 ---------- */
.foot{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:20px;
  padding:40px var(--pad) 28px;
  background:#000;
  color:#fff;
}
.foot p{margin:0;font-size:16px;line-height:1.5;overflow-wrap:break-word}
.foot-brand{font-size:18px;font-weight:700;letter-spacing:.06em}
.foot-host,.foot-key{color:#c4c4c4}
.foot small{
  display:block;
  width:100%;
  margin-top:8px;
  padding-top:14px;
  border-top:1px solid #3a3a3a;
  font-size:16px;
  letter-spacing:.02em;
}
.foot small:nth-of-type(1){grid-column:1 / span 2;align-self:end;color:#c4c4c4}
.foot small:nth-of-type(2){grid-column:3;justify-self:end;align-self:end;text-align:right}
.foot a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  color:#fff;
  text-decoration:none;
  border-bottom:1px solid #5c5c5c;
}
.foot a:hover{background:#fff;color:#000}

/* ---------- 滚动出现 ---------- */
.rv{opacity:0;transform:translateY(14px);transition:opacity .6s ease,transform .6s ease}
.rv.in{opacity:1;transform:none}

/* ---------- 断点 ---------- */
@media (max-width:860px){
  main{grid-template-columns:minmax(0,1fr);column-gap:0}
  .rail{grid-column:1;grid-row:auto;position:static;padding:24px 0}
  main > article:not(.hero):not(.rail){grid-column:1}
  .toc{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 16px}
  .foot{grid-template-columns:minmax(0,1fr);gap:12px}
  .foot small:nth-of-type(1),
  .foot small:nth-of-type(2){grid-column:1;justify-self:start;text-align:left}
}

@media (max-width:520px){
  .hero{min-height:0;padding:28px 0 32px}
  .hero h1{font-size:clamp(1.6rem,8vw,2.1rem)}
  .toc{grid-template-columns:minmax(0,1fr)}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .rv{opacity:1;transform:none;transition:none}
  .overlay,.skip{transition:none}
}

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