@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&family=Space+Grotesk:wght@500;600;700&display=swap');

:root{
  --ink:#000000;
  --paper:#ffffff;
  --line:#000000;
  --rail:224px;
  --gap:clamp(1.2rem,3vw,2.6rem);
  --font:"Space Grotesk","Inter","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,monospace;
}

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

html{scroll-behavior:smooth}

body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font);
  font-size:17px;
  line-height:1.7;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

@media (min-width:900px){
  body{padding-left:var(--rail)}
}

/* ---------- 左栏 ---------- */

.bar{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:.7rem 1rem;
  padding:1rem 1.1rem 1.1rem;
  border-bottom:1px solid var(--line);
  background:var(--paper);
}

@media (min-width:900px){
  .bar{
    position:fixed;
    top:0;
    bottom:0;
    left:0;
    width:var(--rail);
    flex-direction:column;
    flex-wrap:nowrap;
    align-items:stretch;
    justify-content:flex-start;
    gap:1.3rem;
    padding:1.6rem 1.1rem;
    border-bottom:0;
    border-right:1px solid var(--line);
    overflow-y:auto;
  }
}

.brand{
  display:inline-flex;
  align-items:center;
  gap:.55rem;
  min-height:44px;
  padding:.1rem 0;
  font-size:1.35rem;
  font-weight:700;
  letter-spacing:-.05em;
  color:var(--ink);
  text-decoration:none;
}

.brand-mark{
  display:block;
  width:15px;
  height:15px;
  background:var(--ink);
  transform:skewX(-14deg);
  transition:transform .22s ease;
}

.brand:hover .brand-mark{transform:skewX(14deg)}

@media (min-width:900px){
  .brand{font-size:1.65rem}
}

.find{flex:1 1 8rem;min-width:0}

.find input{
  width:100%;
  min-height:44px;
  padding:.5rem .7rem;
  border:1px solid var(--line);
  border-radius:4px;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font);
  font-size:.92rem;
  appearance:none;
  -webkit-appearance:none;
}

.find input::-webkit-search-cancel-button{filter:grayscale(1)}

.find input::placeholder{color:var(--ink);opacity:.45}

.find input:focus{outline:2px solid var(--ink);outline-offset:2px}

.bar-nav{flex:1 1 100%;min-width:0}

.bar-nav p{
  margin:0;
  display:flex;
  gap:.3rem;
  overflow-x:auto;
  padding-bottom:.15rem;
  scrollbar-width:thin;
}

@media (min-width:900px){
  .bar-nav{flex:1 1 auto}
  .bar-nav p{flex-direction:column;gap:.05rem;overflow-x:visible}
}

.bar-nav a{
  display:inline-flex;
  align-items:center;
  gap:.6rem;
  min-height:44px;
  padding:.3rem .6rem;
  border-radius:4px;
  color:var(--ink);
  font-size:.96rem;
  letter-spacing:-.015em;
  text-decoration:none;
  white-space:nowrap;
  transition:background-color .22s ease,color .22s ease;
}

.bar-nav a:hover,
.bar-nav a:focus-visible{background:var(--ink);color:var(--paper)}

.bar-nav .tick{
  display:block;
  width:7px;
  height:7px;
  border:1px solid currentColor;
  transition:transform .22s ease;
}

.bar-nav a:hover .tick{transform:rotate(45deg)}

/* ---------- 版面 ---------- */

.stage{display:grid;grid-template-columns:1fr;min-width:0}

@media (min-width:900px){
  .stage{
    grid-template-columns:var(--rail) minmax(0,1fr);
    column-gap:clamp(1.5rem,4vw,3.5rem);
    padding-right:clamp(1.2rem,3vw,2.6rem);
  }
}

/* ---------- 首屏 ---------- */

.hero{
  display:grid;
  gap:1.5rem;
  padding:2rem 1.1rem 2.2rem;
}

.hero-fig{margin:0;order:2;min-width:0}

.hero-copy{order:1;text-align:center}

.hero-copy h1{
  margin:0;
  font-size:clamp(2.1rem,7vw,3rem);
  font-weight:700;
  line-height:1.03;
  letter-spacing:-.05em;
}

.hero-sub{
  margin:1rem auto 0;
  max-width:32ch;
  font-size:1rem;
  line-height:1.6;
}

.hero-fig img{
  display:block;
  width:100%;
  height:auto;
  aspect-ratio:4/3;
  object-fit:cover;
  border:1px solid var(--line);
  border-radius:4px;
  filter:grayscale(1) contrast(1.04);
  transition:filter .25s ease;
}

.hero-fig img:hover{filter:grayscale(0)}

@media (min-width:900px){
  .hero{
    grid-column:1 / -1;
    grid-template-columns:minmax(0,1.05fr) minmax(0,1fr);
    align-items:center;
    gap:clamp(1.5rem,4vw,3.5rem);
    min-height:100vh;
    padding:clamp(2rem,5vh,4rem) clamp(1.1rem,3vw,2.4rem) clamp(2rem,5vh,4rem) clamp(1.2rem,4vw,3rem);
  }
  .hero--text{grid-template-columns:minmax(0,1fr)}
  .hero-fig{order:1}
  .hero-copy{order:2}
  .hero-copy h1{font-size:clamp(2.6rem,5vw,4.6rem)}
  .hero-sub{font-size:1.05rem}
}

.slash{
  grid-column:1 / -1;
  height:26px;
  margin:2.4rem 0;
  background:var(--ink);
  transform:skewY(-1.6deg);
  transform-origin:center;
}

@media (min-width:900px){
  .slash{height:34px;margin:3.2rem 0}
}

/* ---------- 正文 ---------- */

.doc{
  padding:1.6rem 1.1rem 3rem;
  max-width:74ch;
  font-size:1.02rem;
  line-height:1.8;
  min-width:0;
}

@media (min-width:900px){
  .doc{grid-column:2;grid-row:2;padding:1rem 0 4rem}
}

.doc > div{scroll-margin-top:1.2rem;animation:rise .5s ease both}
.doc > div:nth-child(2){animation-delay:.05s}
.doc > div:nth-child(3){animation-delay:.1s}
.doc > div:nth-child(4){animation-delay:.15s}
.doc > div:nth-child(5){animation-delay:.2s}
.doc > div:nth-child(6){animation-delay:.25s}
.doc > div:nth-child(7){animation-delay:.3s}
.doc > div:nth-child(n+8){animation-delay:.35s}

.doc > div.is-off{display:none}

@keyframes rise{
  from{opacity:0;transform:translateY(14px)}
  to{opacity:1;transform:none}
}

.doc > div + div{
  margin-top:3.2rem;
  padding-top:2.2rem;
  border-top:1px solid var(--line);
}

.doc small{
  display:block;
  margin-bottom:.5rem;
  font-family:var(--mono);
  font-size:.72rem;
  letter-spacing:.22em;
}

.doc h2{
  margin:0 0 .85rem;
  font-size:clamp(1.5rem,3.6vw,2.1rem);
  font-weight:700;
  line-height:1.16;
  letter-spacing:-.04em;
}

.doc h3{
  margin:1.9rem 0 .6rem;
  font-size:1.2rem;
  font-weight:700;
  line-height:1.3;
  letter-spacing:-.02em;
}

.doc p{margin:0 0 1rem}

.doc ul,
.doc ol{margin:0 0 1.2rem;padding-left:1.3rem}

.doc li{margin:.35rem 0}

.doc a{
  color:var(--ink);
  text-decoration:underline;
  text-underline-offset:3px;
  text-decoration-thickness:1px;
  transition:background-color .2s ease,color .2s ease;
}

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

.doc strong{font-weight:700}

.doc blockquote{
  margin:1.4rem 0;
  padding:.2rem 0 .2rem 1.1rem;
  border-left:3px solid var(--line);
}

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

.doc img{
  max-width:100%;
  height:auto;
  border:1px solid var(--line);
  border-radius:4px;
  filter:grayscale(1);
  transition:filter .25s ease;
}

.doc img:hover{filter:grayscale(0)}

.doc figure{margin:1.4rem 0}

.doc figcaption{margin-top:.4rem;font-family:var(--mono);font-size:.82rem}

.doc table{
  width:100%;
  margin:1.2rem 0;
  border-collapse:collapse;
  font-size:.95rem;
}

.doc th,
.doc td{border:1px solid var(--line);padding:.5rem .6rem;text-align:left}

.doc code,
.doc pre{font-family:var(--mono);font-size:.88em}

.doc code{background:#f2f2f2;padding:.1em .35em;border-radius:4px}

.doc pre{background:#f2f2f2;padding:.9rem 1rem;border-radius:4px;overflow-x:auto}

.doc pre code{background:none;padding:0}

.doc hr{border:0;border-top:1px solid var(--line);margin:2rem 0}

/* ---------- 侧栏 ---------- */

.rail{
  padding:1.6rem 1.1rem 2rem;
  border-top:1px solid var(--line);
  min-width:0;
}

@media (min-width:900px){
  .rail{
    grid-column:1;
    grid-row:2;
    border-top:0;
    border-right:1px solid var(--line);
    padding:1.1rem 1.1rem 2rem 0;
    position:sticky;
    top:0;
    align-self:start;
    max-height:100vh;
    overflow-y:auto;
  }
}

.rail small{
  display:block;
  margin-bottom:.4rem;
  font-family:var(--mono);
  font-size:.7rem;
  letter-spacing:.22em;
  opacity:.55;
}

.rail h2{
  margin:0 0 1rem;
  font-size:1.05rem;
  font-weight:700;
  letter-spacing:-.03em;
}

.rail ol{
  margin:0;
  padding:0;
  list-style:none;
  counter-reset:r;
}

.rail li{
  counter-increment:r;
  border-top:1px solid var(--line);
}

.rail li:last-child{border-bottom:1px solid var(--line)}

.rail li a{
  display:flex;
  align-items:center;
  gap:.6rem;
  min-height:42px;
  padding:.35rem 0;
  color:var(--ink);
  font-size:.9rem;
  line-height:1.35;
  text-decoration:none;
  transition:padding-left .22s ease;
}

.rail li a::before{
  content:counter(r,decimal-leading-zero);
  font-family:var(--mono);
  font-size:.7rem;
  opacity:.5;
}

.rail li a:hover{padding-left:.4rem}

/* ---------- 页脚 ---------- */

.site-foot{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:center;
  gap:.3rem 1.4rem;
  padding:1.3rem 1.1rem 2rem;
  border-top:1px solid var(--ink);
  font-size:.9rem;
  text-align:center;
}

.site-foot address{
  font-style:normal;
  font-weight:700;
  letter-spacing:-.03em;
}

.site-foot ul{
  display:flex;
  flex-wrap:wrap;
  gap:.1rem 1rem;
  margin:0;
  padding:0;
  list-style:none;
}

.site-foot li a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 .1rem;
  color:var(--ink);
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:border-color .2s ease;
}

.site-foot li a:hover{border-bottom-color:var(--ink)}

.site-foot .copy{
  display:flex;
  align-items:center;
  gap:.6rem;
  margin:0;
}

.site-foot .copy a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  color:var(--ink);
  text-decoration:none;
  border-bottom:1px solid var(--ink);
}

/* ---------- 动效开关 ---------- */

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-delay:0ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
}

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