/* ===== 01. tokens & reset ===== */
:root{
  --ink:#05100E;
  --panel:#0B1D19;
  --grid:#16332C;
  --white:#F3F8F6;
  --mist:#93A9A2;
  --cyan:#6FF0D4;
  --cyan-deep:#1FA98F;
  --gold:#F2B233;
  --warn:#FF7A4D;
  --mist-cyan:#B8F3E4;

  --rail-w:88px;
  --rail-w-open:248px;
  --pad-x:clamp(18px,4vw,56px);
  --shell:1180px;

  --font-display:"Noto Sans SC","Source Han Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,monospace;
}

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

html{-webkit-text-size-adjust:100%;scroll-padding-top:24px}

body{
  margin:0;
  min-height:100vh;
  background:var(--ink);
  color:var(--white);
  font-family:var(--font-display);
  font-size:16px;
  font-weight:400;
  line-height:1.85;
  letter-spacing:.01em;
  overflow-x:hidden;
}

/* 精密网格 + 轨道侧光 */
body::before{
  content:"";
  position:fixed;
  inset:0;
  z-index:0;
  pointer-events:none;
  background-image:
    linear-gradient(to right,rgba(22,51,44,.55) 1px,transparent 1px),
    linear-gradient(to bottom,rgba(22,51,44,.55) 1px,transparent 1px);
  background-size:64px 64px;
  opacity:.5;
}
body::after{
  content:"";
  position:fixed;
  inset:0;
  z-index:0;
  pointer-events:none;
  background:
    radial-gradient(680px 520px at 0% 42%,rgba(31,169,143,.16),rgba(5,16,14,0) 72%),
    radial-gradient(520px 420px at 92% 6%,rgba(111,240,212,.07),rgba(5,16,14,0) 70%);
}

h1,h2,h3,h4{
  margin:0;
  font-weight:900;
  line-height:1.12;
  letter-spacing:-.02em;
}
p{margin:0 0 1.2em}
p:last-child{margin-bottom:0}
ul,ol{margin:0}
img{max-width:100%}
button{font:inherit;color:inherit}

:focus-visible{
  outline:2px solid var(--cyan);
  outline-offset:2px;
}

::selection{background:rgba(111,240,212,.28);color:var(--white)}

/* ===== 02. 布局容器 ===== */
.page-main{
  position:relative;
  z-index:1;
  margin-inline-start:var(--rail-w);
  padding-block-end:clamp(48px,8vw,96px);
  transition:margin-inline-start .3s cubic-bezier(.4,0,.2,1);
}
.page-shell{
  width:100%;
  max-width:var(--shell);
  margin-inline:auto;
  padding-inline:var(--pad-x);
}

.grid{display:grid;gap:24px}
.grid-12{grid-template-columns:repeat(12,minmax(0,1fr))}

.divider{
  border:0;
  border-top:1px solid var(--grid);
  margin-block:clamp(28px,4vw,48px);
}

/* ===== 03. 通用组件 ===== */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:10px;
  min-height:46px;
  padding:0 22px;
  border:1px solid transparent;
  border-radius:0;
  font-family:var(--font-display);
  font-size:14px;
  font-weight:700;
  letter-spacing:.02em;
  line-height:1.2;
  text-decoration:none;
  cursor:pointer;
  transition:background .18s ease,border-color .18s ease,color .18s ease;
}
.btn--gold{background:var(--gold);color:#05100E}
.btn--gold:hover{background:#FFC85C}
.btn--ghost{background:transparent;border-color:var(--grid);color:var(--white)}
.btn--ghost:hover{border-color:var(--cyan);color:var(--cyan)}

.breadcrumb{margin-block:clamp(20px,3vw,32px) clamp(20px,3vw,32px)}
.breadcrumb-list{
  display:flex;
  flex-wrap:wrap;
  gap:8px;
  margin:0;
  padding:0;
  list-style:none;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  color:var(--mist);
}
.breadcrumb-item{display:flex;align-items:center}
.breadcrumb-item::after{content:"/";margin-inline-start:8px;color:var(--grid)}
.breadcrumb-item:last-child::after{content:""}
.breadcrumb-link{color:var(--mist);text-decoration:none;transition:color .16s ease}
.breadcrumb-link:hover{color:var(--cyan)}

.section-head{
  display:grid;
  grid-template-columns:auto minmax(0,1fr);
  gap:8px 24px;
  align-items:start;
  margin-block-end:clamp(22px,3vw,34px);
}
.section-num{
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.2em;
  color:var(--cyan);
  padding-block-start:.55em;
}
.section-title{font-size:clamp(28px,4vw,44px);font-weight:900}
.section-lead{
  grid-column:2;
  margin:0;
  max-width:62ch;
  color:var(--mist);
  font-size:16px;
  line-height:1.85;
}

.panel{
  background:var(--panel);
  border:1px solid var(--grid);
  border-radius:0;
  padding:clamp(18px,2.4vw,28px);
}

.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:4px 9px;
  border:1px solid var(--grid);
  border-radius:0;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.1em;
  color:var(--mist);
  text-decoration:none;
  transition:border-color .16s ease,color .16s ease;
}
.tag--cyan{border-color:rgba(111,240,212,.45);color:var(--cyan)}

.mono{font-family:var(--font-mono);font-size:13px;letter-spacing:.06em}
.meta{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  color:var(--mist);
}

/* 图片容器：页面阶段放 <img> 即可，自动低饱和暗调 + 底部压暗 */
.media-frame{
  position:relative;
  display:block;
  overflow:hidden;
  border:1px solid var(--grid);
  border-radius:0;
  background:var(--panel);
  aspect-ratio:16/10;
}
.media-frame img{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
  filter:saturate(.62) contrast(1.06) brightness(.84);
}
.media-frame::after{
  content:"";
  position:absolute;
  inset:0;
  pointer-events:none;
  background:linear-gradient(180deg,rgba(5,16,14,0) 42%,rgba(5,16,14,.78) 100%);
}
.media-frame--wide{aspect-ratio:21/9}
.media-frame--tall{aspect-ratio:3/4}
.media-caption{
  margin-block-start:10px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  color:var(--cyan-deep);
  line-height:1.7;
}

/* ===== 04. 跳转链接 ===== */
.skip-link{
  position:fixed;
  top:12px;
  left:12px;
  z-index:999;
  padding:10px 16px;
  background:var(--gold);
  color:#05100E;
  font-size:13px;
  font-weight:700;
  text-decoration:none;
  transform:translateY(-180%);
  transition:transform .2s ease;
}
.skip-link:focus-visible{transform:translateY(0)}

/* ===== 05. 头部：侧边轨道 ===== */
.site-header{
  position:fixed;
  inset-block:0;
  inset-inline-start:0;
  z-index:90;
  width:var(--rail-w);
  display:flex;
  flex-direction:column;
  background:linear-gradient(180deg,#0B1D19 0%,#071614 58%,#05100E 100%);
  border-inline-end:1px solid var(--grid);
  transition:width .3s cubic-bezier(.4,0,.2,1);
}
.site-header::after{
  content:"";
  position:absolute;
  inset-inline-end:-1px;
  top:0;
  width:1px;
  height:96px;
  background:linear-gradient(180deg,var(--cyan),rgba(111,240,212,0));
  pointer-events:none;
}

.read-progress{
  position:fixed;
  top:0;
  left:var(--rail-w);
  right:0;
  height:2px;
  z-index:96;
  pointer-events:none;
  background:rgba(22,51,44,.65);
  transition:left .3s cubic-bezier(.4,0,.2,1);
}
.read-progress-bar{
  display:block;
  width:100%;
  height:100%;
  transform:scaleX(0);
  transform-origin:0 50%;
  background:linear-gradient(90deg,var(--cyan-deep),var(--cyan) 62%,var(--gold));
}

.rail-top{
  display:flex;
  flex-direction:column;
  align-items:center;
  gap:14px;
  padding:16px 12px 14px;
  border-block-end:1px solid var(--grid);
}
body[data-rail="expanded"] .rail-top{align-items:stretch}

.brand{
  display:flex;
  align-items:center;
  justify-content:center;
  gap:12px;
  min-width:0;
  color:var(--white);
  text-decoration:none;
}
body[data-rail="expanded"] .brand{justify-content:flex-start}

.brand-mark{
  position:relative;
  flex:0 0 auto;
  display:block;
  width:42px;
  height:42px;
  border:1px solid var(--grid);
  background:
    radial-gradient(circle at 50% 50%,var(--cyan) 0 3px,rgba(5,16,14,0) 3.5px),
    rgba(111,240,212,.05);
  transition:border-color .18s ease;
}
.brand-mark::before,
.brand-mark::after{
  content:"";
  position:absolute;
  background:var(--cyan);
  opacity:.85;
}
.brand-mark::before{left:50%;top:9px;bottom:9px;width:1px;transform:translateX(-.5px)}
.brand-mark::after{top:50%;left:9px;right:9px;height:1px;transform:translateY(-.5px)}
.brand:hover .brand-mark{border-color:var(--cyan-deep)}

.brand-text{
  display:flex;
  flex-direction:column;
  gap:2px;
  min-width:0;
  max-width:0;
  opacity:0;
  overflow:hidden;
  transition:max-width .28s ease,opacity .18s ease;
}
body[data-rail="expanded"] .brand-text{max-width:180px;opacity:1}

.brand-name{
  font-size:15px;
  font-weight:900;
  letter-spacing:.02em;
  white-space:nowrap;
  line-height:1.3;
}
.brand-tag{
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.14em;
  color:var(--mist);
  white-space:nowrap;
  line-height:1.4;
}

.rail-toggle{
  display:flex;
  align-items:center;
  justify-content:center;
  gap:6px;
  width:100%;
  height:30px;
  padding:0;
  border:1px solid var(--grid);
  border-radius:0;
  background:rgba(22,51,44,.35);
  color:var(--mist);
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.14em;
  cursor:pointer;
  transition:border-color .18s ease,color .18s ease,background .18s ease;
}
.rail-toggle:hover{border-color:var(--cyan-deep);color:var(--cyan);background:rgba(31,169,143,.1)}
.rail-toggle-glyph{
  display:inline-block;
  font-size:12px;
  line-height:1;
  transition:transform .25s ease;
}
body[data-rail="expanded"] .rail-toggle-glyph{transform:rotate(180deg)}
.rail-toggle-text{
  max-width:0;
  overflow:hidden;
  white-space:nowrap;
  opacity:0;
  transition:max-width .28s ease,opacity .18s ease;
}
body[data-rail="expanded"] .rail-toggle-text{max-width:90px;opacity:1}

.nav-toggle{
  display:none;
  align-items:center;
  gap:10px;
  padding:10px 12px;
  border:1px solid var(--grid);
  border-radius:0;
  background:rgba(22,51,44,.5);
  color:var(--cyan);
  cursor:pointer;
}
.nav-toggle-bars{
  position:relative;
  display:block;
  width:20px;
  height:12px;
}
.nav-toggle-bars::before,
.nav-toggle-bars::after{
  content:"";
  position:absolute;
  left:0;
  right:0;
  height:1px;
  background:var(--cyan);
  transition:transform .2s ease,top .2s ease,bottom .2s ease;
}
.nav-toggle-bars::before{top:0}
.nav-toggle-bars::after{bottom:0}
.site-header[data-open="true"] .nav-toggle-bars::before{top:5px;transform:rotate(45deg)}
.site-header[data-open="true"] .nav-toggle-bars::after{bottom:6px;transform:rotate(-45deg)}
.nav-toggle-text{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.16em;
}

.site-nav{
  flex:1;
  display:flex;
  flex-direction:column;
  min-height:0;
  padding-block:16px 0;
  overflow-y:auto;
  overscroll-behavior:contain;
  scrollbar-width:thin;
  scrollbar-color:var(--grid) transparent;
}

.nav-kicker{
  display:none;
  margin:0 0 12px;
  padding-inline:20px;
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.28em;
  color:var(--cyan-deep);
}
body[data-rail="expanded"] .nav-kicker{display:block}

.nav-list{list-style:none;margin:0;padding:0}
.nav-item{margin:0}

.nav-link{
  position:relative;
  display:flex;
  align-items:center;
  justify-content:center;
  gap:10px;
  padding:11px 12px;
  border-inline-start:1px solid transparent;
  color:var(--mist);
  text-decoration:none;
  transition:color .18s ease,background .18s ease,border-color .18s ease;
}
body[data-rail="expanded"] .nav-link{
  justify-content:flex-start;
  padding-inline:20px;
}
.nav-link:hover{color:var(--white);background:rgba(22,51,44,.4)}

.nav-num{
  flex:0 0 auto;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.1em;
  color:var(--cyan-deep);
  line-height:1.6;
  transition:color .18s ease;
}
.nav-link:hover .nav-num,
.nav-link[aria-current="page"] .nav-num{color:var(--cyan)}

.nav-label{
  max-width:0;
  opacity:0;
  overflow:hidden;
  white-space:nowrap;
  font-size:14px;
  font-weight:500;
  line-height:1.6;
  transition:max-width .28s ease,opacity .18s ease;
}
body[data-rail="expanded"] .nav-label{max-width:180px;opacity:1}

.nav-link[aria-current="page"]{
  color:var(--white);
  background:linear-gradient(90deg,rgba(111,240,212,.13),rgba(111,240,212,0) 82%);
  border-inline-start-color:var(--cyan);
}

/* 本页章节刻度 */
.rail-toc{
  margin-block-start:18px;
  padding-block-start:14px;
  border-block-start:1px solid var(--grid);
}
.rail-toc[hidden]{display:none}
.toc-kicker{
  display:none;
  margin:0 0 8px;
  padding-inline:20px;
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.24em;
  color:var(--mist);
}
body[data-rail="expanded"] .toc-kicker{display:block}
.toc-list{list-style:none;margin:0;padding:0}
.toc-item{margin:0}
.toc-btn{
  display:flex;
  align-items:center;
  gap:8px;
  width:100%;
  padding:7px 20px;
  border:0;
  border-inline-start:1px solid transparent;
  background:transparent;
  color:var(--mist);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.08em;
  text-align:start;
  cursor:pointer;
  transition:color .16s ease,border-color .16s ease;
}
.toc-btn:hover{color:var(--white)}
.toc-btn[aria-current="true"]{color:var(--cyan);border-inline-start-color:var(--cyan)}
.toc-num{flex:0 0 auto;color:var(--cyan-deep);font-size:10px}
.toc-btn[aria-current="true"] .toc-num{color:var(--cyan)}
.toc-text{
  overflow:hidden;
  text-overflow:ellipsis;
  white-space:nowrap;
  max-width:0;
  opacity:0;
  transition:max-width .28s ease,opacity .18s ease;
}
body[data-rail="expanded"] .toc-text{max-width:150px;opacity:1}

.rail-foot{
  margin-block-start:auto;
  display:grid;
  gap:10px;
  padding:16px 12px 20px;
  border-block-start:1px solid var(--grid);
}

.rail-cta{
  display:flex;
  align-items:center;
  justify-content:center;
  min-height:40px;
  padding:10px 8px;
  background:var(--gold);
  color:#05100E;
  font-size:13px;
  font-weight:700;
  letter-spacing:.02em;
  text-align:center;
  text-decoration:none;
  line-height:1.3;
  transition:background .18s ease;
}
.rail-cta:hover{background:#FFC85C}
body:not([data-rail="expanded"]) .rail-cta{
  writing-mode:vertical-rl;
  text-orientation:mixed;
  letter-spacing:.26em;
  min-height:132px;
  padding:18px 8px;
}

.rail-meta{
  display:flex;
  align-items:center;
  gap:6px;
  margin:0;
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.1em;
  color:var(--mist);
  line-height:1.5;
  justify-content:center;
}
.rail-dot{
  width:5px;
  height:5px;
  flex:0 0 auto;
  background:var(--cyan);
  box-shadow:0 0 0 3px rgba(111,240,212,.14);
}

.signal-toggle{
  display:flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  width:100%;
  padding:9px 6px;
  border:1px solid var(--grid);
  border-radius:0;
  background:rgba(11,29,25,.85);
  color:var(--mist);
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.06em;
  line-height:1.4;
  text-align:start;
  cursor:pointer;
  transition:border-color .18s ease,color .18s ease;
}
.signal-toggle:hover{border-color:var(--warn);color:var(--warn)}
.signal-toggle[aria-pressed="true"]{border-color:var(--warn);color:var(--warn);background:rgba(255,122,77,.1)}
.signal-dot{
  width:6px;
  height:6px;
  flex:0 0 auto;
  background:currentColor;
  transition:box-shadow .18s ease;
}
.signal-toggle[aria-pressed="true"] .signal-dot{box-shadow:0 0 0 3px rgba(255,122,77,.2)}
.signal-text{
  max-width:0;
  overflow:hidden;
  white-space:nowrap;
  opacity:0;
  transition:max-width .28s ease,opacity .18s ease;
}
body[data-rail="expanded"] .signal-text{max-width:150px;opacity:1;white-space:normal}

/* 信号开关打开时，页面可用的状态钩子 */
body[data-signal="on"] .is-live{
  border-color:var(--warn);
  box-shadow:inset 2px 0 0 var(--warn);
}

/* ===== 06. 页脚 ===== */
.site-footer{
  position:relative;
  z-index:1;
  margin-inline-start:var(--rail-w);
  border-block-start:1px solid var(--grid);
  background:linear-gradient(180deg,#071614 0%,#05100E 100%);
  padding:clamp(40px,6vw,80px) var(--pad-x) 28px;
  transition:margin-inline-start .3s cubic-bezier(.4,0,.2,1);
}
.site-footer::before{
  content:"";
  position:absolute;
  inset-inline:0;
  top:-1px;
  height:1px;
  background:linear-gradient(90deg,rgba(111,240,212,0),var(--cyan-deep) 22%,rgba(111,240,212,.1) 70%);
  pointer-events:none;
}
.foot-inner{
  width:100%;
  max-width:var(--shell);
  margin-inline:auto;
}

.foot-head{
  display:grid;
  grid-template-columns:minmax(0,1.05fr) minmax(0,1.55fr);
  gap:clamp(28px,4vw,64px);
  align-items:start;
}

.foot-wordmark{
  margin:0 0 6px;
  font-size:clamp(52px,8vw,96px);
  font-weight:900;
  line-height:.92;
  letter-spacing:-.03em;
  color:#122C26;
  -webkit-text-stroke:1px #2B5148;
}
.foot-name{
  margin:0 0 6px;
  font-size:18px;
  font-weight:900;
  letter-spacing:.02em;
}
.foot-slogan{
  margin:0 0 18px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  color:var(--mist);
  line-height:1.8;
}
.foot-cta{
  display:inline-flex;
  align-items:center;
  gap:8px;
  min-height:42px;
  padding:0 18px;
  border:1px solid var(--grid);
  color:var(--white);
  font-size:13px;
  font-weight:700;
  text-decoration:none;
  transition:border-color .18s ease,color .18s ease;
}
.foot-cta::before{content:"";width:6px;height:6px;background:var(--cyan);flex:0 0 auto}
.foot-cta:hover{border-color:var(--cyan);color:var(--cyan)}

.foot-nav{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:clamp(18px,3vw,34px);
}
.foot-col-title{
  margin:0 0 12px;
  padding-block-end:8px;
  border-block-end:1px solid var(--grid);
  font-family:var(--font-mono);
  font-size:10px;
  font-weight:500;
  letter-spacing:.24em;
  color:var(--cyan);
}
.foot-links{list-style:none;margin:0;padding:0}
.foot-links li{margin:0}
.foot-link{
  display:inline-flex;
  align-items:baseline;
  gap:8px;
  padding-block:5px;
  color:var(--mist);
  font-size:14px;
  text-decoration:none;
  transition:color .16s ease;
}
.foot-link::before{
  content:"";
  width:5px;
  height:5px;
  flex:0 0 auto;
  background:var(--grid);
  transform:translateY(-2px);
  transition:background .16s ease;
}
.foot-link:hover{color:var(--white)}
.foot-link:hover::before{background:var(--cyan)}

.foot-tags{
  display:flex;
  flex-wrap:wrap;
  gap:8px;
  margin-block-start:clamp(28px,4vw,48px);
}
.foot-tag-chip{
  padding:5px 10px;
  border:1px solid var(--grid);
  background:rgba(11,29,25,.6);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.08em;
  color:var(--mist);
}

.foot-contact{
  display:grid;
  grid-template-columns:minmax(0,180px) minmax(0,1fr) auto;
  gap:clamp(18px,3vw,44px);
  align-items:start;
  margin-block-start:clamp(30px,4vw,52px);
  padding-block-start:clamp(20px,3vw,28px);
  border-block-start:1px solid var(--grid);
}
.foot-contact-title{
  margin:0;
  font-family:var(--font-mono);
  font-size:11px;
  font-weight:500;
  letter-spacing:.2em;
  color:var(--cyan);
  line-height:1.9;
}
.contact-list{list-style:none;margin:0;padding:0;display:grid;gap:10px}
.contact-item{
  display:grid;
  grid-template-columns:56px minmax(0,1fr);
  gap:12px;
  align-items:baseline;
}
.contact-key{
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.16em;
  color:var(--cyan-deep);
}
.contact-val{
  font-size:13px;
  color:var(--mist);
  line-height:1.75;
}
.contact-val--strong{color:var(--white);font-family:var(--font-mono);font-size:12.5px;letter-spacing:.02em}

.foot-top{
  align-self:start;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  min-height:40px;
  padding:0 16px;
  border:1px solid var(--grid);
  border-radius:0;
  background:transparent;
  color:var(--mist);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  cursor:pointer;
  white-space:nowrap;
  transition:border-color .18s ease,color .18s ease;
}
.foot-top:hover{border-color:var(--cyan);color:var(--cyan)}

.foot-legal{
  display:flex;
  flex-wrap:wrap;
  align-items:baseline;
  gap:8px 20px;
  margin-block-start:clamp(26px,3vw,38px);
  padding-block-start:18px;
  border-block-start:1px solid var(--grid);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.1em;
  color:var(--mist);
  line-height:1.8;
}
.legal-line{margin:0;color:var(--cyan-deep)}
.legal-note{margin:0;flex:1 1 280px;color:var(--mist)}
.legal-copy{margin:0;color:var(--mist)}

/* ===== 07. 响应式 ===== */
@media (min-width:900px){
  body[data-rail="expanded"]{--rail-w:var(--rail-w-open)}
}

@media (max-width:1023px){
  .foot-head{grid-template-columns:minmax(0,1fr);gap:clamp(26px,4vw,40px)}
  .foot-contact{grid-template-columns:minmax(0,1fr) auto;gap:20px}
  .foot-contact-title{grid-column:1 / -1}
}

@media (max-width:899px){
  :root{--rail-w:0px}

  .site-header{
    inset-block:0 auto;
    inset-inline:0;
    width:100%;
    height:64px;
    flex-direction:row;
    align-items:center;
    padding-inline:16px;
    border-inline-end:0;
    border-block-end:1px solid var(--grid);
    background:#071614;
  }
  .site-header::after{display:none}

  .read-progress{left:0;top:64px}

  .rail-top{
    flex:1;
    flex-direction:row;
    align-items:center;
    gap:12px;
    padding:0;
    border:0;
  }
  body[data-rail="expanded"] .rail-top{align-items:center}
  .brand{justify-content:flex-start}
  body[data-rail="expanded"] .brand{justify-content:flex-start}
  .brand-mark{width:34px;height:34px}
  .brand-text{max-width:none;opacity:1}
  .brand-name{font-size:14px}
  .brand-tag{font-size:9px;letter-spacing:.1em}
  .rail-toggle{display:none}
  .nav-toggle{display:flex;margin-inline-start:auto}

  .site-nav{
    position:fixed;
    inset-block:64px 0;
    inset-inline-start:0;
    z-index:95;
    width:min(84vw,330px);
    padding-block:20px 0;
    background:#071614;
    border-inline-end:1px solid var(--grid);
    transform:translateX(-102%);
    transition:transform .3s cubic-bezier(.4,0,.2,1);
  }
  .site-header[data-open="true"] .site-nav{transform:translateX(0)}

  .nav-kicker{display:block}
  .toc-kicker{display:block}
  .nav-link{justify-content:flex-start;padding-inline:20px}
  .nav-label{max-width:none;opacity:1}
  .toc-text{max-width:none;opacity:1}
  .signal-text{max-width:none;opacity:1;white-space:normal}
  body:not([data-rail="expanded"]) .rail-cta{
    writing-mode:horizontal-tb;
    letter-spacing:.06em;
    min-height:44px;
    padding:10px 12px;
  }

  .page-main{margin-inline-start:0;padding-block-start:64px}
  .site-footer{margin-inline-start:0}

  .grid-12{grid-template-columns:repeat(6,minmax(0,1fr))}
  .section-head{grid-template-columns:minmax(0,1fr);gap:6px}
  .section-lead{grid-column:1}
  .foot-nav{grid-template-columns:repeat(3,minmax(0,1fr))}
}

@media (max-width:639px){
  body{font-size:15.5px}
  .grid{gap:18px}
  .grid-12{grid-template-columns:repeat(2,minmax(0,1fr))}
  .foot-nav{grid-template-columns:repeat(2,minmax(0,1fr))}
  .foot-contact{grid-template-columns:minmax(0,1fr)}
  .contact-item{grid-template-columns:minmax(0,1fr);gap:2px}
  .contact-key{padding-block-start:4px}
  .foot-top{justify-self:start;margin-block-start:8px}
  .foot-legal{flex-direction:column;align-items:flex-start}
  .brand-name{max-width:42vw;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
  .media-frame{aspect-ratio:4/3}
}

/* ===== 08. 动效降级 ===== */
@media (prefers-reduced-motion: reduce){
  *,
  *::before,
  *::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  html{scroll-behavior:auto}
}