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

:root{
  --ink:#000;
  --paper:#fff;
  --wash:#f4f4f4;
  --gray:#6d6d6d;
  --hair:#dcdcdc;
  --mono:"Fira Code",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --sans:"Fira Sans",-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --shadow:0 26px 52px -34px rgba(0,0,0,.62);
  --r:28px;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%;overflow-x:clip}
body{
  margin:0;background:var(--paper);color:var(--ink);
  font-family:var(--sans);font-size:17px;line-height:1.72;
  -webkit-font-smoothing:antialiased;overflow-x:clip;
}
img,svg,video,iframe{display:block;max-width:100%;height:auto}
a{color:inherit}
menu,ul,ol{list-style:none}
h1,h2,h3{font-family:var(--mono);font-weight:700;line-height:1.12;letter-spacing:-.01em;margin:0;overflow-wrap:break-word}
p{margin:0 0 1.1em}
:focus-visible{outline:2px solid var(--ink);outline-offset:2px}
.sr-only{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:fixed;left:1rem;top:-5rem;z-index:80;
  background:var(--ink);color:var(--paper);text-decoration:none;
  padding:.7rem 1rem;font-family:var(--mono);font-size:.88rem;
}
.skip:focus{top:.6rem}

/* ---------- 顶栏 ---------- */
.top{
  position:sticky;top:0;z-index:40;display:flex;align-items:center;gap:.7rem;
  padding:.55rem clamp(.75rem,3vw,1.6rem);
  background:var(--paper);border-bottom:2px solid var(--ink);
  max-width:100%;
}
.top > *{min-width:0}
.mark{
  flex:0 0 auto;display:inline-flex;align-items:center;justify-content:center;
  width:42px;height:42px;min-height:42px;background:var(--ink);color:var(--paper);
  text-decoration:none;font-family:var(--mono);font-weight:700;font-size:1.05rem;
}
.mark img{width:26px;height:26px;object-fit:contain;filter:invert(1)}
.mark.small{width:36px;height:36px;min-height:36px;font-size:.9rem}
.mark:hover{background:var(--paper);color:var(--ink);box-shadow:inset 0 0 0 2px var(--ink)}
.mark:hover img{filter:none}

.find{
  display:flex;align-items:center;gap:.35rem;flex:1 1 0;min-width:0;
  margin-left:auto;max-width:21rem;
}
.find input{
  flex:1 1 0;min-width:0;width:100%;height:42px;padding:0 .8rem;
  font-family:var(--mono);font-size:.92rem;color:var(--ink);
  background:var(--paper);border:1.5px solid var(--ink);border-radius:999px;
}
.find input::placeholder{color:#8a8a8a}
.find button{
  flex:0 0 auto;height:42px;min-width:44px;padding:0 .55rem;cursor:pointer;
  font-family:var(--mono);font-size:.92rem;
  background:var(--ink);color:var(--paper);border:1.5px solid var(--ink);border-radius:999px;
}
.find button:hover{background:var(--paper);color:var(--ink)}

.nav{position:relative;flex:0 0 auto}
.nav summary{
  display:inline-flex;align-items:center;gap:.5rem;
  height:42px;min-height:42px;padding:0 .85rem;cursor:pointer;
  list-style:none;border:1.5px solid var(--ink);border-radius:999px;
  font-family:var(--mono);font-size:.9rem;
}
.nav summary::-webkit-details-marker{display:none}
.bars{position:relative;display:block;width:15px;height:2px;background:currentColor}
.bars::before,.bars::after{content:'';position:absolute;left:0;width:15px;height:2px;background:currentColor}
.bars::before{top:-5px}
.bars::after{top:5px}
.nav details[open] > summary{background:var(--ink);color:var(--paper)}
.nav menu{
  position:absolute;right:0;top:calc(100% + .55rem);z-index:50;
  width:min(90vw,24rem);max-width:calc(100vw - 1.6rem);
  margin:0;padding:.6rem;
  display:grid;grid-template-columns:1fr 1fr;gap:.2rem;
  background:var(--paper);border:2px solid var(--ink);border-radius:var(--r);
  box-shadow:var(--shadow);
}
.nav menu a{
  display:flex;align-items:center;min-height:46px;padding:.45rem .7rem;
  text-decoration:none;font-size:.94rem;border-bottom:1px solid var(--hair);
  overflow-wrap:break-word;
}
.nav menu a:hover,.nav menu a:focus-visible{background:var(--ink);color:var(--paper)}

/* ---------- 首屏 ---------- */
.hero{
  position:relative;overflow:hidden;overflow:clip;isolation:isolate;
  min-height:100vh;min-height:100svh;max-width:100%;
  display:grid;grid-template-columns:1.12fr .88fr;align-items:center;
  gap:clamp(1.5rem,4vw,4rem);
  padding:clamp(1.6rem,7vh,5rem) clamp(1rem,4vw,3.5rem) clamp(2rem,7vh,4.5rem);
  border-bottom:3px solid var(--ink);
}
.hero > *{min-width:0}
.ghost{
  position:absolute;right:0;bottom:.04em;z-index:-1;
  font-family:var(--mono);font-weight:700;line-height:.8;
  font-size:clamp(3.4rem,15vw,13rem);white-space:nowrap;
  color:rgba(0,0,0,.055);pointer-events:none;user-select:none;
}
.hero-copy{max-width:34ch}
.hero h1{font-size:clamp(2.05rem,6.4vw,4.3rem);letter-spacing:-.035em}
.lede{
  margin-top:1.3rem;max-width:32ch;padding-left:1rem;
  border-left:3px solid var(--ink);
  font-size:clamp(1rem,2vw,1.12rem);line-height:1.68;color:#161616;
  overflow-wrap:break-word;
}
.hero-plate{
  position:relative;overflow:hidden;align-self:center;
  aspect-ratio:4/5;max-height:76vh;min-width:0;
  background:var(--wash);border:2px solid var(--ink);border-radius:var(--r);
  box-shadow:var(--shadow);
}
.hero-plate img{width:100%;height:100%;object-fit:cover}
.hero-plate::after{
  content:'';position:absolute;inset:0;pointer-events:none;
  background-image:radial-gradient(#000 1px,transparent 1.1px);
  background-size:5px 5px;opacity:.17;mix-blend-mode:multiply;
}

/* ---------- 主体 ---------- */
main{
  counter-reset:sec;
  display:grid;grid-template-columns:minmax(0,1fr) 16.5rem;
  gap:clamp(1.5rem,4vw,3.5rem);align-items:start;
  max-width:82rem;margin:0 auto;
  padding:clamp(2rem,5vw,4rem) clamp(1rem,4vw,2.6rem) clamp(3rem,7vw,5rem);
}
main > *{min-width:0}
article{min-width:0;overflow-wrap:break-word}
article > *{max-width:100%}
article > div{
  position:relative;
  padding-block:clamp(1.9rem,4vw,3rem);
  border-top:2px solid var(--ink);
  scroll-margin-top:5.5rem;
  counter-increment:sec;
}
article > div:first-of-type{border-top:0;padding-top:0}
article > div::before{
  content:counter(sec,decimal-leading-zero);
  position:absolute;left:-3.2rem;top:clamp(2rem,4vw,3.2rem);
  font-family:var(--mono);font-size:.78rem;letter-spacing:.12em;color:var(--gray);
}
article h2{font-size:clamp(1.5rem,3.4vw,2.15rem);margin-bottom:.7em}
article h2 > span{display:inline-block;padding-bottom:.14em;box-shadow:inset 0 -.3em 0 rgba(0,0,0,.13)}
article h3{font-size:clamp(1.12rem,2.2vw,1.32rem);margin:1.4em 0 .55em;letter-spacing:0}
article p{max-width:70ch}
article ul,article ol{list-style:none;padding-left:1.2rem}
article ul li,article ol li{position:relative;margin:.35em 0;max-width:68ch}
article ul > li::before{content:'·';position:absolute;left:-1rem;font-weight:700}
article ol{counter-reset:li}
article ol > li{counter-increment:li}
article ol > li::before{content:counter(li) '.';position:absolute;left:-1.4rem;font-family:var(--mono);font-size:.82rem}
article a{text-decoration:underline;text-underline-offset:.2em;text-decoration-thickness:2px;overflow-wrap:break-word}
article a:hover{background:var(--ink);color:var(--paper);text-decoration:none}
article blockquote{
  margin:1.7rem 0;padding:.5rem 0 .5rem 1.2rem;
  border-left:6px solid var(--ink);
  font-size:1.14rem;line-height:1.6;font-style:italic;
}
article blockquote p{max-width:none}
article figure{margin:1.8rem 0;border:2px solid var(--ink);border-radius:var(--r);overflow:hidden;background:var(--wash)}
article figure img{width:100%}
article figcaption{padding:.7rem 1rem;border-top:1px solid var(--hair);font-family:var(--mono);font-size:.8rem;color:var(--gray)}
article table{
  display:block;width:100%;max-width:100%;overflow-x:auto;
  border-collapse:collapse;font-size:.95rem;margin:1.4rem 0;
  -webkit-overflow-scrolling:touch;
}
article th,article td{border-bottom:1px solid var(--hair);padding:.6rem .5rem;text-align:left}
article th{font-family:var(--mono);font-size:.85rem}
article code,article pre{font-family:var(--mono);font-size:.88em;background:var(--wash);overflow-wrap:break-word}
article pre{max-width:100%;overflow:auto;padding:1rem;border-radius:14px;white-space:pre-wrap}
article pre code{white-space:inherit}

/* ---------- 侧栏 ---------- */
.rail{
  position:sticky;top:5.4rem;min-width:0;
  padding:1.1rem 1.05rem 1.3rem;
  background:var(--paper);border:2px solid var(--ink);border-radius:var(--r);
  box-shadow:var(--shadow);
}
.rail h2{font-size:.9rem;letter-spacing:.2em}
.rail h2 > span{display:inline-block;padding-bottom:.35rem;border-bottom:2px solid var(--ink)}
.rail ol{counter-reset:toc;margin:.95rem 0 0;padding:0}
.rail li + li{margin-top:.1rem}
.rail a{
  display:flex;align-items:baseline;gap:.55rem;min-height:40px;min-width:0;
  padding:.45rem .3rem;overflow-wrap:break-word;
  text-decoration:none;font-size:.92rem;border-bottom:1px dashed var(--hair);
  transition:opacity .25s ease,background .2s ease,color .2s ease;
}
.rail a::before{
  flex:0 0 auto;
  counter-increment:toc;content:counter(toc,decimal-leading-zero);
  font-family:var(--mono);font-size:.72rem;color:var(--gray);
}
.rail a:hover,.rail a:focus-visible{background:var(--ink);color:var(--paper)}
.rail a:hover::before,.rail a:focus-visible::before{color:#c9c9c9}
.rail a.dim{opacity:.32}

/* ---------- 页脚 ---------- */
.foot{
  display:flex;flex-wrap:wrap;align-items:center;justify-content:center;
  gap:.5rem 1.1rem;max-width:100%;
  padding:1.5rem clamp(1rem,4vw,2.6rem);
  border-top:3px solid var(--ink);
}
.foot nav{min-width:0;max-width:100%}
.foot nav ul{display:flex;flex-wrap:wrap;justify-content:center;gap:.15rem .9rem;margin:0;padding:0}
.foot nav a{
  display:inline-flex;align-items:center;min-height:40px;
  font-family:var(--mono);font-size:.84rem;text-decoration:none;
}
.foot nav a:hover{text-decoration:underline;text-underline-offset:.28em}
.copy{
  flex:1 0 100%;text-align:center;
  font-family:var(--mono);font-size:.78rem;letter-spacing:.08em;color:var(--gray);
}

/* ---------- 动效 ---------- */
.reveal{opacity:0;transform:translateY(16px);transition:opacity .7s ease,transform .7s ease}
.reveal.in{opacity:1;transform:none}

/* ---------- 断点 ---------- */
@media (min-width:961px){
  article > div > p{column-width:19rem;column-gap:2.4rem}
  article > div:first-of-type > p:first-of-type::first-letter{
    float:left;font-family:var(--mono);font-weight:700;
    font-size:3.2em;line-height:.82;margin:.05em .1em 0 0;
  }
}
@media (max-width:960px){
  main{grid-template-columns:minmax(0,1fr)}
  .rail{position:static;order:-1}
  article > div::before{position:static;display:block;margin-bottom:.6rem}
  .rail ol{display:grid;grid-template-columns:1fr 1fr;gap:.1rem .8rem}
  .rail li + li{margin-top:0}
}
@media (max-width:800px){
  .hero{grid-template-columns:minmax(0,1fr);min-height:auto;padding-top:2rem;gap:1.6rem}
  .hero-plate{aspect-ratio:16/11;max-height:44vh;order:2}
  .ghost{bottom:auto;top:.4em;right:0;font-size:clamp(2.4rem,11vw,6rem);opacity:.9}
  .lede{margin-top:1rem}
}
@media (max-width:560px){
  body{font-size:16.5px}
  .top{gap:.5rem;padding:.5rem .7rem}
  .find{max-width:none}
  .find button{display:none}
  .nav menu{width:calc(100vw - 1.4rem);max-width:calc(100vw - 1.4rem)}
  .rail ol{grid-template-columns:1fr}
  article > div{padding-block:1.7rem}
  article h2{font-size:1.42rem}
  .foot nav ul{gap:0 .7rem}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
}

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