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

:root{
  --ink:#000000;
  --l1:#0b0b0b;
  --l2:#121212;
  --mid:#08111a;
  --line:#232323;
  --fg:#ededed;
  --dim:#8f8f8f;
  --neon:#7fe3ff;
  color-scheme:dark;
}

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

html{
  background:var(--ink);
  scroll-behavior:smooth;
  overflow-x:clip;
  -webkit-text-size-adjust:100%;
}

body{
  margin:0;
  background:var(--ink);
  color:var(--fg);
  font-family:Inter,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  font-size:16px;
  line-height:1.7;
  font-weight:400;
  letter-spacing:.005em;
  -webkit-font-smoothing:antialiased;
  overflow-x:clip;
}

a{color:inherit;text-decoration:none}
img{display:block;max-width:100%}
h1,h2,h3{line-height:1.25;letter-spacing:-.02em;margin:0}
p{margin:0}
ul,ol{margin:0;padding:0;list-style:none}

a:focus-visible,
button:focus-visible{
  outline:2px solid var(--neon);
  outline-offset:3px;
  border-radius:6px;
}

main [id]{scroll-margin-top:70px}

/* 顶栏 */
.masthead{
  background:var(--ink);
  border-bottom:1px solid var(--line);
  padding:8px 16px;
}

.nav{
  display:grid;
  grid-template-columns:1fr auto 1fr;
  align-items:center;
  gap:8px;
  max-width:1180px;
  margin:0 auto;
}

.menu{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:2px;
}
.menu--l{justify-content:flex-end}
.menu--r{justify-content:flex-start}

.menu a{
  display:inline-flex;
  align-items:center;
  gap:7px;
  min-height:44px;
  padding:0 9px;
  font-size:16px;
  color:var(--dim);
  transition:color .2s ease;
}
.menu a:hover{color:#fff}

.dot{
  width:5px;
  height:5px;
  flex:0 0 auto;
  background:#3a3a3a;
  border-radius:1px;
  transform:rotate(45deg);
  transition:background .2s ease,box-shadow .2s ease;
}
.menu a:hover .dot{background:var(--neon);box-shadow:0 0 8px var(--neon)}

.menu__cta{
  margin-left:6px;
  padding:0 13px !important;
  color:var(--fg) !important;
  border:1px solid var(--line);
  border-radius:10px;
}
.menu__cta:hover{border-color:var(--neon);color:#fff !important}

.brand{
  display:inline-flex;
  align-items:center;
  gap:9px;
  min-height:44px;
  padding:6px 12px;
  font-size:17px;
  font-weight:600;
  letter-spacing:.08em;
  white-space:nowrap;
}
.brand__mark{
  width:13px;
  height:13px;
  border:1px solid var(--neon);
  transform:rotate(45deg);
  box-shadow:0 0 10px rgba(127,227,255,.45);
}

/* 二级粘性锚点条 */
.rail{
  position:sticky;
  top:0;
  z-index:30;
  background:rgba(8,8,8,.94);
  border-bottom:1px solid var(--line);
  backdrop-filter:blur(8px);
}
.rail__row{
  display:flex;
  gap:2px;
  max-width:1180px;
  margin:0 auto;
  padding:0 12px;
  overflow-x:auto;
  scrollbar-width:thin;
}
.rail__a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 12px;
  font-size:16px;
  color:var(--dim);
  white-space:nowrap;
  border-bottom:2px solid transparent;
  transition:color .2s ease,border-color .2s ease;
}
.rail__a:hover,
.rail__a.is-on{color:#fff;border-bottom-color:var(--neon)}

/* 首屏 */
.hero{
  display:grid;
  grid-template-columns:1.05fr .95fr;
  align-items:center;
  gap:clamp(20px,4vw,54px);
  min-height:45vh;
  max-width:1120px;
  margin:0 auto;
  padding:clamp(26px,5vw,54px) 20px;
}

.hero__txt{text-align:center}

.hero__kicker{
  margin-bottom:10px;
  font-size:16px;
  letter-spacing:.32em;
  color:var(--neon);
  text-shadow:0 0 10px rgba(127,227,255,.35);
}

.hero h1{
  font-size:clamp(1.85rem,5.3vw,3rem);
  font-weight:600;
  letter-spacing:-.035em;
  color:#fff;
  text-shadow:0 0 26px rgba(127,227,255,.16);
}

.hero__lede{
  margin:14px auto 0;
  max-width:34ch;
  color:var(--dim);
}

.hero__jump{
  display:flex;
  flex-wrap:wrap;
  justify-content:center;
  gap:10px;
  margin-top:20px;
}
.hero__jump a{
  display:inline-flex;
  align-items:center;
  min-height:42px;
  padding:0 16px;
  font-size:16px;
  color:var(--fg);
  background:var(--l2);
  border:1px solid var(--line);
  border-radius:10px;
  transition:border-color .2s ease,box-shadow .2s ease;
}
.hero__jump a:hover{
  border-color:var(--neon);
  box-shadow:0 0 16px rgba(127,227,255,.18);
}

.hero__media{
  position:relative;
  margin:0;
  aspect-ratio:16 / 11;
  border-radius:10px;
  overflow:hidden;
  border:1px solid var(--line);
  background:linear-gradient(150deg,var(--mid),var(--l2) 55%,#000);
  box-shadow:0 20px 44px rgba(0,0,0,.75),inset 0 0 0 1px rgba(255,255,255,.03);
}

.frames{
  position:absolute;
  inset:-10% 0;
  transform:translate3d(0,var(--py,0px),0);
  will-change:transform;
}
.frames img{
  position:absolute;
  inset:0;
  width:100%;
  height:100%;
  object-fit:cover;
  opacity:1;
}
.frames--multi img{
  opacity:0;
  animation:xf 21s linear infinite;
}
.frames--multi img:nth-child(1){animation-delay:0s}
.frames--multi img:nth-child(2){animation-delay:7s}
.frames--multi img:nth-child(3){animation-delay:14s}

@keyframes xf{
  0%{opacity:0}
  3%{opacity:1}
  30%{opacity:1}
  33%{opacity:0}
  100%{opacity:0}
}

.frames--empty::after{
  content:"";
  position:absolute;
  inset:0;
  background:repeating-linear-gradient(135deg,rgba(127,227,255,.16) 0 2px,transparent 2px 15px);
}

.band{
  height:12px;
  max-width:1120px;
  margin:0 auto;
  background:linear-gradient(90deg,var(--neon),rgba(127,227,255,.1) 55%,transparent);
  clip-path:polygon(0 40%,100% 0,100% 60%,0 100%);
  opacity:.8;
}

/* 正文骨架 */
.shell{
  display:grid;
  grid-template-columns:220px minmax(0,1fr);
  gap:clamp(24px,4vw,48px);
  max-width:1120px;
  margin:0 auto;
  padding:clamp(26px,4vw,52px) 20px 64px;
}

.side{
  position:sticky;
  top:70px;
  align-self:start;
  border-left:1px solid var(--line);
  padding-left:16px;
}
.side__h{font-size:16px;letter-spacing:.2em;color:#fff}
.subtitle{margin-top:4px;font-size:16px;letter-spacing:.1em;color:var(--neon)}

.side__list{margin-top:14px;counter-reset:s}
.side__list li{counter-increment:s}
.side__list a{
  display:flex;
  align-items:center;
  gap:9px;
  min-height:40px;
  font-size:16px;
  color:var(--dim);
  transition:color .2s ease;
}
.side__list a::before{
  content:counter(s,decimal-leading-zero);
  font-size:13px;
  letter-spacing:.06em;
  color:#4d4d4d;
}
.side__list a:hover{color:#fff}
.side__list a:hover::before{color:var(--neon)}

.side__back{margin-top:16px}
.side__back a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  font-size:16px;
  color:var(--dim);
  border-bottom:1px solid var(--line);
}
.side__back a:hover{color:#fff}

.prose{min-width:0}
.prose > section{padding:34px 0;border-top:1px solid var(--line)}
.prose > section:first-child{border-top:0;padding-top:0}

.prose h2{
  font-size:clamp(1.28rem,3vw,1.7rem);
  font-weight:600;
  color:#fff;
  margin-bottom:10px;
}
.prose h3{
  font-size:1.14rem;
  font-weight:600;
  color:#fff;
  margin:22px 0 8px;
}
.prose p{margin:12px 0;color:#d6d6d6}
.prose ul,.prose ol{margin:12px 0;padding-left:1.25em;color:#d6d6d6}
.prose ul{list-style:square}
.prose ol{list-style:decimal}
.prose li{margin:6px 0}
.prose a{
  color:var(--neon);
  border-bottom:1px solid rgba(127,227,255,.35);
}
.prose a:hover{background:rgba(127,227,255,.1)}
.prose strong{color:#fff}
.prose img{margin:14px 0;border-radius:10px;border:1px solid var(--line)}
.prose figure{margin:16px 0}
.prose figcaption{font-size:16px;color:var(--dim);margin-top:6px}
.prose blockquote{
  margin:16px 0;
  padding:12px 16px;
  background:var(--l1);
  border-left:2px solid var(--neon);
  border-radius:0 10px 10px 0;
  color:#c8c8c8;
}
.prose table{
  display:block;
  width:100%;
  overflow-x:auto;
  border-collapse:collapse;
  margin:16px 0;
  font-size:16px;
}
.prose th,.prose td{border:1px solid var(--line);padding:8px 10px;text-align:left}
.prose th{color:#fff;background:var(--l2)}
.prose code{background:var(--l2);padding:1px 5px;border-radius:4px;font-size:.94em}
.prose hr{border:0;border-top:1px solid var(--line);margin:24px 0}

/* 页脚 */
.foot{
  display:grid;
  grid-template-columns:1.5fr 1fr 1fr;
  gap:26px 24px;
  max-width:1120px;
  margin:0 auto;
  padding:44px 20px 0;
  border-top:1px solid var(--line);
}

.foot__big{
  font-size:clamp(2.1rem,8.5vw,4.4rem);
  font-weight:700;
  line-height:1;
  letter-spacing:-.05em;
  color:#fff;
  text-shadow:0 0 30px rgba(127,227,255,.14);
}

.foot__h{
  font-size:16px;
  font-weight:500;
  letter-spacing:.22em;
  color:var(--dim);
  margin-bottom:10px;
}

.foot__nav a,
.foot__meta a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  font-size:16px;
  color:#cfcfcf;
}
.foot__nav a:hover,
.foot__meta a:hover{color:var(--neon)}

.foot__bar{
  grid-column:1 / -1;
  border-top:1px solid var(--line);
  padding:16px 0 22px;
  font-size:16px;
  color:#6f6f6f;
}

@media (max-width:860px){
  .nav{display:flex;flex-wrap:wrap;justify-content:center}
  .brand{order:-1;flex:0 0 100%;justify-content:center}
  .menu{flex:1 1 auto;justify-content:center}

  .hero{grid-template-columns:1fr;padding-top:22px}
  .hero__media{aspect-ratio:16 / 9}

  .shell{grid-template-columns:1fr;padding-top:24px}
  .prose{order:1}
  .side{
    order:2;
    position:static;
    border-left:0;
    border-top:1px solid var(--line);
    padding-left:0;
    padding-top:18px;
  }

  .foot{
    grid-template-columns:1fr;
    padding-top:34px;
    gap:18px;
  }
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .frames{transform:none !important}
  .frames img{animation:none !important;opacity:1}
  .frames--multi img + img{display:none}
}

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