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

:root{
  --ink:#000000;
  --paper:#ffffff;
  --line:rgba(255,255,255,.15);
  --line-2:rgba(255,255,255,.34);
  --glass:rgba(255,255,255,.055);
  --r:10px;
  --u:8px;
  --max:1360px;
  --dock-h:76px;
}

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

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

body{
  margin:0;
  font-family:"Space Grotesk","Helvetica Neue",Helvetica,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  font-size:17px;
  line-height:1.6;
  color:var(--paper);
  background-color:var(--ink);
  background-image:radial-gradient(95% 60% at 86% -12%,rgba(255,255,255,.14),rgba(255,255,255,0) 64%);
  background-repeat:no-repeat;
  padding-bottom:calc(var(--dock-h) + env(safe-area-inset-bottom));
  overflow-x:clip;
  -webkit-font-smoothing:antialiased;
}

a{color:inherit;text-decoration:none}
menu{margin:0;padding:0;list-style:none}
img{max-width:100%;height:auto;border-radius:8px}
:focus-visible{outline:2px solid var(--paper);outline-offset:2px}

/* 底部固定条 */
.dock{
  position:fixed;
  left:0;right:0;bottom:0;
  z-index:60;
  display:grid;
  grid-template-columns:1fr auto 1fr;
  align-items:center;
  gap:var(--u);
  padding:10px 16px calc(10px + env(safe-area-inset-bottom));
  background:rgba(0,0,0,.76);
  -webkit-backdrop-filter:blur(16px);
  backdrop-filter:blur(16px);
  border-top:1px solid var(--line);
}

.dock-a{justify-self:start;display:flex}
.dock-b{justify-self:end;display:flex;gap:8px}

.brand{
  justify-self:center;
  display:inline-flex;
  align-items:center;
  gap:8px;
  min-height:40px;
  padding:0 10px;
  font-size:16px;
  font-weight:600;
  letter-spacing:.01em;
  white-space:nowrap;
}
.brand-dot{
  width:8px;height:8px;flex:none;
  border-radius:50%;
  background:var(--paper);
}

.menu{position:relative}
.menu summary{
  list-style:none;
  display:inline-flex;
  align-items:center;
  gap:9px;
  min-height:40px;
  padding:0 16px;
  font-size:16px;
  font-weight:500;
  cursor:pointer;
  border:1px solid var(--line-2);
  border-radius:999px;
  background:var(--glass);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
  transition:background .18s,color .18s,border-color .18s;
}
.menu summary::-webkit-details-marker{display:none}
.menu summary::after{
  content:"";
  width:8px;height:8px;
  border-right:2px solid currentColor;
  border-bottom:2px solid currentColor;
  transform:rotate(45deg) translate(-2px,-2px);
}
.menu summary:hover{background:rgba(255,255,255,.14)}
.menu[open] summary{background:var(--paper);color:var(--ink);border-color:var(--paper)}
.menu[open] summary::after{transform:rotate(225deg) translate(-2px,-2px)}

.menu menu{
  position:absolute;
  left:0;
  bottom:calc(100% + 10px);
  min-width:196px;
  display:grid;
  gap:2px;
  padding:8px;
  border:1px solid var(--line-2);
  border-radius:var(--r);
  background:rgba(10,10,10,.94);
  -webkit-backdrop-filter:blur(18px);
  backdrop-filter:blur(18px);
}
.menu menu a{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:0 12px;
  font-size:16px;
  border-radius:8px;
}
.menu menu a:hover,
.menu menu a:focus-visible{background:rgba(255,255,255,.14)}

.pill{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:0 16px;
  font-size:16px;
  border:1px solid var(--line);
  border-radius:999px;
  background:var(--glass);
  transition:background .18s,color .18s,border-color .18s;
}
.pill:hover,
.pill:focus-visible{background:var(--paper);color:var(--ink);border-color:var(--paper)}

/* 首屏 */
.hero{
  min-height:70svh;
  display:flex;
  flex-direction:column;
  justify-content:flex-end;
  align-items:flex-end;
  text-align:right;
  padding:96px 24px 56px;
  border-bottom:1px solid var(--line);
  background-image:repeating-linear-gradient(to right,rgba(255,255,255,.07) 0 1px,transparent 1px 12.5%);
}
.hero h1{
  margin:0;
  max-width:16ch;
  font-size:clamp(2rem,8.4vw,6.4rem);
  font-weight:700;
  line-height:.94;
  letter-spacing:-.035em;
  text-wrap:balance;
  word-break:break-word;
}
.hero-p{
  margin:20px 0 0;
  max-width:44ch;
  font-size:16px;
  line-height:1.6;
  color:rgba(255,255,255,.7);
}

/* 主体网格 */
main{padding:0}
.wrap{
  max-width:var(--max);
  margin:0 auto;
  padding:48px 24px 72px;
  display:grid;
  grid-template-columns:minmax(0,1fr) 264px;
  gap:48px;
  align-items:start;
}
.stage{min-width:0}
.body{max-width:70ch}

/* 正文 */
.body{counter-reset:sec}
.body > div{
  position:relative;
  counter-increment:sec;
  margin:0 0 16px;
  padding:26px 26px 30px;
  border:1px solid var(--line);
  border-radius:var(--r);
  background:var(--glass);
  -webkit-backdrop-filter:blur(12px);
  backdrop-filter:blur(12px);
}
.body > div::before{
  content:counter(sec,decimal-leading-zero);
  position:absolute;
  top:20px;right:22px;
  font-size:12px;
  letter-spacing:.2em;
  color:rgba(255,255,255,.5);
}
.body > div > :first-child{margin-top:0}
.body > div > :last-child{margin-bottom:0}
.body h2{
  margin:0 0 14px;
  padding-right:44px;
  font-size:clamp(1.45rem,3.1vw,2.05rem);
  font-weight:700;
  line-height:1.16;
  letter-spacing:-.02em;
}
.body h2 > span{display:inline}
.body h3{
  margin:24px 0 8px;
  font-size:1.18rem;
  font-weight:600;
  line-height:1.3;
}
.body h3 > span{display:inline}
.body p{margin:0 0 14px}
.body ul,.body ol{margin:0 0 14px;padding-left:1.35em}
.body li{margin-bottom:6px}
.body a{border-bottom:1px solid var(--line-2)}
.body strong{font-weight:600}
.body img{margin:6px 0 14px}
.body blockquote{
  margin:0 0 14px;
  padding:2px 0 2px 16px;
  border-left:2px solid var(--line-2);
  color:rgba(255,255,255,.8);
}
.body table{width:100%;border-collapse:collapse;margin:0 0 14px;font-size:16px}
.body th,.body td{padding:8px 10px;border-bottom:1px solid var(--line);text-align:left}

div[id]{scroll-margin-bottom:104px;scroll-margin-top:24px}

/* 侧栏 */
.rail{
  position:sticky;
  top:24px;
  padding:20px;
  border:1px solid var(--line);
  border-radius:var(--r);
  background:var(--glass);
  -webkit-backdrop-filter:blur(12px);
  backdrop-filter:blur(12px);
}
.rail-h{
  margin:0 0 12px;
  font-size:16px;
  font-weight:600;
  letter-spacing:.16em;
}
.rail-h > span{display:inline}
.rail-list{display:grid;gap:2px}
.rail-list a{
  display:flex;
  align-items:center;
  min-height:40px;
  padding:0 10px;
  font-size:16px;
  border-radius:8px;
  color:rgba(255,255,255,.78);
  transition:background .18s,color .18s;
}
.rail-list a:hover,
.rail-list a:focus-visible{background:rgba(255,255,255,.12);color:var(--paper)}

/* 页脚 */
.foot{
  max-width:var(--max);
  margin:0 auto;
  padding:56px 24px 40px;
  border-top:1px solid var(--line);
  display:grid;
  grid-template-columns:repeat(4,minmax(0,1fr));
  gap:32px;
}
.foot h2{
  margin:0 0 10px;
  font-size:16px;
  font-weight:600;
  letter-spacing:.12em;
}
.foot h2 > span{display:inline}
.foot menu{display:grid}
.foot menu a{
  display:flex;
  align-items:center;
  min-height:40px;
  font-size:16px;
  color:rgba(255,255,255,.76);
}
.foot menu a:hover,
.foot menu a:focus-visible{color:var(--paper);text-decoration:underline;text-underline-offset:4px}
.foot p{margin:0;font-size:16px;color:rgba(255,255,255,.62)}
.copy{
  grid-column:1/-1;
  margin:24px 0 0;
  padding-top:20px;
  border-top:1px solid var(--line);
  text-align:center;
  font-size:16px;
  color:rgba(255,255,255,.55);
}

/* 动效 */
.reveal{
  opacity:0;
  transform:translateY(16px);
  transition:opacity .5s ease,transform .5s cubic-bezier(.2,.7,.3,1);
}
.reveal.in{opacity:1;transform:none}
.body > div.reveal:nth-child(2){transition-delay:.05s}
.body > div.reveal:nth-child(3){transition-delay:.1s}
.body > div.reveal:nth-child(4){transition-delay:.15s}
.body > div.reveal:nth-child(5){transition-delay:.2s}
.body > div.reveal:nth-child(6){transition-delay:.25s}
.body > div.reveal:nth-child(7){transition-delay:.3s}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  .body > div.reveal{transition-delay:0s}
}

/* 断点 */
@media (max-width:960px){
  .wrap{grid-template-columns:minmax(0,1fr);gap:28px}
  .rail{position:static;order:2}
  .body{max-width:none}
}

@media (max-width:860px){
  .dock-b{display:none}
  .hero{min-height:62svh;padding:88px 18px 40px}
  .wrap{padding:32px 18px 56px}
  .body > div{padding:22px 18px 26px}
  .body > div::before{top:16px;right:16px}
  .body h2{padding-right:38px}
}

@media (max-width:720px){
  .foot{grid-template-columns:repeat(2,minmax(0,1fr));gap:24px;padding:44px 18px 32px}
}

@media (max-width:420px){
  .brand{font-size:16px;padding:0 4px}
  .hero h1{letter-spacing:-.02em}
}

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