/* ==========================================================================
   球帝带安装 · 共享站点样式 /assets/site.css
   画布：深空蓝连续底色 / 锚点：信号青 / 状态：琥珀橙 / 分层：低饱和紫灰
   ========================================================================== */

/* 1. 设计变量 */
:root{
  --space-950:#071426;
  --space-900:#0A1B31;
  --space-800:#0E2340;
  --ink-900:#030912;
  --cyan:#35E0CF;
  --cyan-soft:#9BF4EA;
  --amber:#FFB24A;
  --violet:#7C7899;
  --fog:#EEF3FA;
  --slate:#A7B3C7;

  --line-soft:rgba(124,120,153,.22);
  --line-mid:rgba(124,120,153,.38);
  --line-cyan:rgba(53,224,207,.34);

  --font-display:"Noto Sans SC","PingFang SC","Hiragino Sans GB","Source Han Sans SC","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-body:var(--font-display);
  --font-mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono","Courier New",monospace;

  --maxw:1180px;
  --gutter:clamp(18px,4vw,48px);
  --radius-s:6px;
  --radius-m:14px;
  --radius-l:26px;
  --shadow-soft:0 26px 64px -34px rgba(3,9,18,.92);
  --ease:cubic-bezier(.22,.61,.36,1);
}

/* 2. Reset 与基础 */
*,*::before,*::after{ box-sizing:border-box; }
html{
  -webkit-text-size-adjust:100%;
  text-size-adjust:100%;
  scroll-behavior:smooth;
  scroll-padding-top:172px;
}
body,h1,h2,h3,h4,p,ul,ol,li,figure,blockquote,dl,dd,fieldset{ margin:0; }
ul,ol{ padding:0; }
img,svg,picture,video{ max-width:100%; }
button{ font:inherit; color:inherit; background:none; border:0; }
a{ color:inherit; }
::selection{ background:rgba(53,224,207,.26); color:var(--fog); }

body{
  font-family:var(--font-body);
  font-size:clamp(16px,1.05vw,17px);
  line-height:1.75;
  color:var(--fog);
  background-color:var(--space-950);
  background-image:
    radial-gradient(120% 78% at 84% -12%, rgba(53,224,207,.12), transparent 62%),
    radial-gradient(88% 62% at 6% 2%, rgba(124,120,153,.16), transparent 66%);
  min-height:100vh;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

h1,h2,h3,h4{
  font-family:var(--font-display);
  font-weight:800;
  letter-spacing:-.02em;
  line-height:1.18;
  color:var(--fog);
}
h1{ font-size:clamp(32px,5.2vw,58px); }
h2{ font-size:clamp(24px,3.2vw,36px); }
h3{ font-size:clamp(18px,2vw,24px); }
p{ max-width:72ch; }
strong{ font-weight:700; color:var(--fog); }

.mono{
  font-family:var(--font-mono);
  font-weight:500;
  font-size:12.5px;
  letter-spacing:.12em;
  font-variant-numeric:tabular-nums;
}

:where(a,button,summary,[tabindex]):focus-visible{
  outline:2px solid var(--cyan);
  outline-offset:3px;
  border-radius:3px;
}

.skip-link{
  position:fixed;
  top:8px;
  left:8px;
  z-index:200;
  padding:10px 18px;
  border-radius:999px;
  background:var(--cyan);
  color:#04121F;
  font-weight:700;
  font-size:14px;
  text-decoration:none;
  transform:translateY(-160%);
  transition:transform .18s var(--ease);
}
.skip-link:focus{ transform:translateY(0); }

/* 3. 刊头 */
.site-header{
  position:sticky;
  top:0;
  z-index:60;
  background:rgba(7,20,38,.94);
  border-bottom:1px solid var(--line-soft);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
}

.header-meta{
  background:var(--ink-900);
  border-bottom:1px solid rgba(124,120,153,.18);
}
.header-meta__inner{
  max-width:var(--maxw);
  margin:0 auto;
  padding:7px var(--gutter);
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:18px;
  font-size:12px;
  color:var(--slate);
}
.header-meta__index{
  max-width:none;
  color:var(--slate);
  letter-spacing:.06em;
}
.header-meta__index .mono{ color:var(--cyan); }
.header-meta__domain{
  max-width:none;
  color:var(--violet);
  letter-spacing:.16em;
  text-transform:uppercase;
}
.header-meta__link{
  max-width:none;
  display:inline-flex;
  align-items:center;
  gap:6px;
  color:var(--cyan-soft);
  font-size:12px;
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:color .18s var(--ease), border-color .18s var(--ease);
}
.header-meta__link:hover{ color:var(--amber); border-color:var(--amber); }

.masthead__inner{
  max-width:var(--maxw);
  margin:0 auto;
  padding:16px var(--gutter) 14px;
  display:grid;
  grid-template-columns:1fr auto 1fr;
  grid-template-areas:"aside brand cta";
  align-items:center;
  gap:16px;
}
.masthead__aside{
  grid-area:aside;
  justify-self:start;
  max-width:none;
  color:var(--violet);
  letter-spacing:.18em;
}
.brand-lockup{
  grid-area:brand;
  display:flex;
  flex-direction:column;
  align-items:center;
  gap:5px;
  padding:2px 10px;
  text-align:center;
  text-decoration:none;
}
.brand-name{
  font-family:var(--font-display);
  font-weight:800;
  font-size:clamp(22px,2.5vw,30px);
  letter-spacing:-.01em;
  line-height:1.1;
  color:var(--fog);
  transition:color .18s var(--ease);
}
.brand-name::before{
  content:"";
  display:inline-block;
  width:.4em;
  height:.4em;
  margin-right:.4em;
  border-radius:2px;
  background:var(--cyan);
  transform:translateY(-.3em);
}
.brand-lockup:hover .brand-name{ color:var(--cyan-soft); }
.brand-tagline{
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.16em;
  color:var(--slate);
}
.masthead__cta{ grid-area:cta; justify-self:end; }

.nav-toggle{
  grid-area:toggle;
  justify-self:end;
  display:none;
  align-items:center;
  gap:9px;
  padding:9px 13px;
  border:1px solid var(--line-cyan);
  border-radius:999px;
  color:var(--cyan-soft);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  cursor:pointer;
  transition:border-color .18s var(--ease), color .18s var(--ease), background-color .18s var(--ease);
}
.nav-toggle:hover{ border-color:var(--cyan); color:var(--fog); background:rgba(53,224,207,.1); }
.nav-toggle__bars{ display:grid; gap:4px; }
.nav-toggle__bars i{
  display:block;
  width:18px;
  height:2px;
  border-radius:2px;
  background:currentColor;
  transition:transform .18s var(--ease), opacity .18s var(--ease);
}
.nav-toggle__label{ line-height:1; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1){ transform:translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2){ opacity:0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3){ transform:translateY(-6px) rotate(-45deg); }

.site-nav{
  border-top:1px solid rgba(124,120,153,.18);
  background:linear-gradient(180deg, rgba(14,35,64,.55), rgba(7,20,38,0));
}
.site-nav__list{
  max-width:var(--maxw);
  margin:0 auto;
  padding:0 var(--gutter);
  list-style:none;
  display:flex;
  flex-wrap:wrap;
  justify-content:center;
  gap:clamp(4px,1.6vw,26px);
}
.site-nav__item{ display:block; }
.site-nav__link{
  position:relative;
  display:inline-block;
  padding:12px 6px 13px;
  font-size:14.5px;
  letter-spacing:.02em;
  color:var(--slate);
  text-decoration:none;
  transition:color .18s var(--ease);
}
.site-nav__link::after{
  content:"";
  position:absolute;
  left:6px;
  right:6px;
  bottom:6px;
  height:1px;
  background:var(--cyan);
  transform:scaleX(0);
  transform-origin:left center;
  transition:transform .2s var(--ease), background-color .2s var(--ease);
}
.site-nav__link:hover{ color:var(--fog); }
.site-nav__link:hover::after{ transform:scaleX(1); }
.site-nav__link[aria-current="page"]{ color:var(--cyan); }
.site-nav__link[aria-current="page"]::after{ transform:scaleX(1); background:var(--amber); }

/* 4. 页脚 */
.site-footer{
  background:var(--ink-900);
  border-top:1px solid var(--line-cyan);
  color:var(--slate);
  margin-top:clamp(48px,7vw,96px);
}
.site-footer__inner{
  max-width:var(--maxw);
  margin:0 auto;
  padding:clamp(44px,6vw,72px) var(--gutter) 26px;
}
.site-footer__top{
  display:grid;
  grid-template-columns:minmax(200px,1.15fr) repeat(3,minmax(110px,.62fr)) minmax(230px,1.2fr);
  gap:clamp(24px,3vw,46px);
  align-items:start;
}
.footer-brand-block{ display:grid; gap:10px; align-content:start; }
.footer-brand{
  font-family:var(--font-display);
  font-weight:800;
  font-size:clamp(20px,2vw,25px);
  letter-spacing:-.01em;
  color:var(--fog);
  text-decoration:none;
  transition:color .18s var(--ease);
}
.footer-brand:hover{ color:var(--cyan); }
.footer-index{
  max-width:none;
  color:var(--violet);
  font-size:11px;
  letter-spacing:.2em;
  line-height:1.9;
}
.footer-col{ display:block; }
.footer-col__title{
  margin:0 0 14px;
  font-family:var(--font-mono);
  font-weight:500;
  font-size:11.5px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--cyan);
}
.footer-col__list{
  list-style:none;
  display:grid;
  gap:9px;
}
.footer-col__link{
  font-size:14.5px;
  color:var(--slate);
  text-decoration:none;
  transition:color .18s var(--ease), padding-left .18s var(--ease);
}
.footer-col__link:hover{ color:var(--amber); padding-left:4px; }

.footer-contact{ display:grid; gap:8px; align-content:start; }
.footer-contact__title{
  margin:0 0 6px;
  font-family:var(--font-mono);
  font-weight:500;
  font-size:11.5px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--cyan);
}
.contact-row{
  max-width:none;
  display:grid;
  grid-template-columns:42px minmax(0,1fr);
  gap:8px;
  font-size:14px;
  line-height:1.6;
}
.contact-row__label{
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.14em;
  color:var(--violet);
  padding-top:2px;
}
.contact-row__value{ color:var(--fog); overflow-wrap:anywhere; }
.contact-row__value.mono{ font-size:13px; letter-spacing:.08em; }
.footer-contact__note{
  max-width:none;
  margin:6px 0 14px;
  font-size:12.5px;
  line-height:1.8;
  color:var(--slate);
}

.site-footer__legal{
  margin-top:clamp(32px,4vw,52px);
  padding-top:20px;
  border-top:1px solid rgba(124,120,153,.24);
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:12px 26px;
  font-size:12.5px;
}
.legal-copy{ max-width:none; color:var(--violet); letter-spacing:.02em; }
.legal-links{
  list-style:none;
  display:flex;
  flex-wrap:wrap;
  gap:8px 20px;
}
.legal-links__link{
  color:var(--slate);
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:color .18s var(--ease), border-color .18s var(--ease);
}
.legal-links__link:hover{ color:var(--cyan-soft); border-color:var(--line-cyan); }

/* 5. 页面容器与章节节奏 */
.page{ display:block; }
.page__inner{
  width:100%;
  max-width:var(--maxw);
  margin:0 auto;
  padding:0 var(--gutter);
}
.section{ padding:clamp(56px,8vw,104px) 0; }
.section--tight{ padding:clamp(36px,5vw,64px) 0; }
.section--band{
  background:linear-gradient(180deg, rgba(14,35,64,.9), rgba(14,35,64,.55));
  border-top:1px solid var(--line-soft);
  border-bottom:1px solid var(--line-soft);
}
.section-title{
  margin:0 0 14px;
  font-family:var(--font-display);
  font-weight:800;
  font-size:clamp(26px,3.4vw,38px);
  letter-spacing:-.02em;
  line-height:1.16;
}
.lede{
  max-width:62ch;
  font-size:clamp(16px,1.4vw,17.5px);
  line-height:1.8;
  color:var(--slate);
}
.eyebrow{
  display:inline-flex;
  align-items:center;
  gap:10px;
  margin-bottom:14px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--cyan);
}
.eyebrow::before{
  content:"";
  width:22px;
  height:1px;
  background:currentColor;
  opacity:.75;
}
.coord{
  font-family:var(--font-mono);
  font-size:12.5px;
  letter-spacing:.16em;
  color:var(--violet);
  font-variant-numeric:tabular-nums;
}
.prose{ max-width:72ch; }
.prose p{ margin:0 0 1.15em; color:var(--slate); }
.prose p:last-child{ margin-bottom:0; }
.prose h3{ margin:1.6em 0 .6em; }
.prose ul,.prose ol{ margin:0 0 1.2em; padding-left:1.4em; color:var(--slate); }
.prose ul{ list-style:disc; }
.prose ol{ list-style:decimal; }
.prose li{ margin-bottom:.45em; }
.prose a{
  color:var(--cyan-soft);
  text-decoration:none;
  border-bottom:1px solid var(--line-cyan);
}
.prose a:hover{ color:var(--amber); border-color:var(--amber); }
.divider{
  height:1px;
  border:0;
  margin:clamp(32px,5vw,64px) 0;
  background:linear-gradient(90deg, var(--line-mid), rgba(124,120,153,0));
}

/* 6. 按钮 */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:.55em;
  padding:12px 22px;
  border:1px solid transparent;
  border-radius:999px;
  font-family:var(--font-body);
  font-size:15px;
  font-weight:600;
  line-height:1.2;
  letter-spacing:.01em;
  text-decoration:none;
  cursor:pointer;
  transition:background-color .18s var(--ease), color .18s var(--ease), border-color .18s var(--ease), transform .18s var(--ease);
}
.btn:hover{ transform:translateY(-1px); }
.btn:active{ transform:translateY(0); }
.btn--cyan{ background:var(--cyan); border-color:var(--cyan); color:#04121F; }
.btn--cyan:hover{ background:var(--cyan-soft); border-color:var(--cyan-soft); }
.btn--ghost{ background:transparent; border-color:rgba(53,224,207,.5); color:var(--cyan-soft); }
.btn--ghost:hover{ background:rgba(53,224,207,.12); border-color:var(--cyan); color:var(--fog); }
.btn--amber{ background:rgba(255,178,74,.14); border-color:rgba(255,178,74,.6); color:var(--amber); }
.btn--amber:hover{ background:rgba(255,178,74,.24); border-color:var(--amber); color:#1A1004; }
.btn--sm{ padding:9px 16px; font-size:13.5px; }

/* 7. 面包屑 */
.breadcrumbs{ padding:22px 0 0; }
.breadcrumbs__list{
  list-style:none;
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.12em;
  color:var(--violet);
}
.breadcrumbs__item{ display:inline-flex; align-items:center; gap:8px; }
.breadcrumbs__item[aria-current="page"]{ color:var(--cyan-soft); }
.breadcrumbs__link{
  color:var(--slate);
  text-decoration:none;
  transition:color .18s var(--ease);
}
.breadcrumbs__link:hover{ color:var(--cyan); }
.breadcrumbs__sep{ color:var(--violet); opacity:.7; }

/* 8. 栅格 */
.grid{ display:grid; gap:clamp(18px,2.4vw,32px); }
.grid--2{ grid-template-columns:repeat(2,minmax(0,1fr)); }
.grid--3{ grid-template-columns:repeat(3,minmax(0,1fr)); }
.split{
  display:grid;
  grid-template-columns:5fr 7fr;
  gap:clamp(24px,3.6vw,56px);
  align-items:start;
}
.rail{
  display:grid;
  grid-template-columns:3fr 9fr;
  gap:clamp(22px,3vw,48px);
  align-items:start;
}
.rail__aside{ position:sticky; top:172px; }

/* 9. 内容组件 */
.card{
  background:rgba(14,35,64,.72);
  border:1px solid var(--line-soft);
  border-radius:var(--radius-m);
  padding:clamp(18px,2.2vw,28px);
  box-shadow:var(--shadow-soft);
}
.card--flush{
  background:transparent;
  border:0;
  border-left:1px solid var(--line-mid);
  border-radius:0;
  padding:2px 0 2px 22px;
  box-shadow:none;
}
.panel{
  background:linear-gradient(160deg, rgba(14,35,64,.95), rgba(7,20,38,.9));
  border-radius:var(--radius-l);
  padding:clamp(22px,3vw,40px);
  border:1px solid var(--line-soft);
}
.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:4px 10px;
  border-radius:999px;
  background:rgba(124,120,153,.22);
  color:var(--fog);
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.1em;
}
.tag--cyan{ background:rgba(53,224,207,.16); color:var(--cyan-soft); }
.tag--amber{ background:rgba(255,178,74,.16); color:var(--amber); }

.timeline{
  list-style:none;
  position:relative;
  display:grid;
  gap:clamp(18px,2.4vw,30px);
}
.timeline::before{
  content:"";
  position:absolute;
  left:7px;
  top:10px;
  bottom:10px;
  width:1px;
  background:linear-gradient(180deg, var(--cyan), rgba(124,120,153,.28));
}
.timeline__item{
  position:relative;
  padding-left:34px;
}
.timeline__item::before{
  content:"";
  position:absolute;
  left:2px;
  top:.62em;
  width:11px;
  height:11px;
  border-radius:50%;
  background:var(--space-950);
  border:2px solid var(--cyan);
}
.timeline__item[data-state="current"]::before{
  background:var(--amber);
  border-color:var(--amber);
  box-shadow:0 0 0 4px rgba(255,178,74,.16);
}
.timeline__meta{
  display:block;
  margin-bottom:4px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.12em;
  color:var(--slate);
}

.stat__num{
  display:block;
  font-family:var(--font-mono);
  font-weight:500;
  font-size:clamp(28px,3.6vw,40px);
  line-height:1.1;
  letter-spacing:-.02em;
  color:var(--cyan);
  font-variant-numeric:tabular-nums;
}
.stat__label{
  display:block;
  margin-top:6px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  color:var(--slate);
}

.chapter-toc{ position:relative; }
.chapter-toc__list{
  list-style:none;
  display:grid;
  gap:2px;
}
.chapter-toc__link{
  display:block;
  padding:8px 12px 8px 14px;
  border-left:1px solid var(--line-mid);
  color:var(--slate);
  font-size:14px;
  text-decoration:none;
  transition:color .16s var(--ease), border-color .16s var(--ease), background-color .16s var(--ease);
}
.chapter-toc__link:hover{ color:var(--fog); border-color:var(--cyan); background:rgba(53,224,207,.06); }
.chapter-toc__link[aria-current="true"]{ color:var(--amber); border-color:var(--amber); }

/* 10. 图片容器基础规则 */
.media-frame{
  position:relative;
  display:block;
  width:100%;
  overflow:hidden;
  aspect-ratio:16/10;
  border:1px solid var(--line-soft);
  border-radius:var(--radius-m);
  background-color:var(--space-800);
  background-image:
    linear-gradient(158deg, rgba(14,35,64,.96), rgba(7,20,38,.98)),
    repeating-linear-gradient(90deg, rgba(53,224,207,.09) 0 1px, transparent 1px 46px),
    repeating-linear-gradient(0deg, rgba(124,120,153,.1) 0 1px, transparent 1px 46px);
}
.media-frame > img,
.media-frame > picture,
.media-frame > picture > img,
.media-frame > svg,
.media-frame > video{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
}
.media-frame--wide{ aspect-ratio:16/9; }
.media-frame--square{ aspect-ratio:1/1; }
.media-frame--tall{ aspect-ratio:4/5; }
.media-frame--line::after{
  content:"";
  position:absolute;
  left:0;
  right:0;
  bottom:24%;
  height:1px;
  background:linear-gradient(90deg, transparent, rgba(53,224,207,.6), transparent);
}
.media-frame__caption{
  max-width:none;
  margin:10px 0 0;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.1em;
  color:var(--slate);
}

/* 11. JS 生成组件 */
.scroll-progress{
  position:fixed;
  top:0;
  left:0;
  right:0;
  height:2px;
  z-index:90;
  pointer-events:none;
  background:transparent;
}
.scroll-progress__bar{
  display:block;
  width:100%;
  height:100%;
  transform:scaleX(0);
  transform-origin:0 50%;
  background:linear-gradient(90deg, var(--cyan), var(--amber));
}
.to-top{
  position:fixed;
  right:clamp(14px,3vw,30px);
  bottom:clamp(14px,3vw,30px);
  z-index:90;
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:10px 16px;
  border-radius:999px;
  border:1px solid rgba(53,224,207,.45);
  background:rgba(14,35,64,.95);
  color:var(--cyan-soft);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  cursor:pointer;
  opacity:0;
  visibility:hidden;
  transform:translateY(10px);
  transition:opacity .2s var(--ease), transform .2s var(--ease), visibility .2s var(--ease), border-color .18s var(--ease), color .18s var(--ease);
}
.to-top[data-visible]{
  opacity:1;
  visibility:visible;
  transform:translateY(0);
}
.to-top:hover{ border-color:var(--cyan); color:var(--fog); }

/* 12. 平板 */
@media (max-width:1080px){
  .site-footer__top{
    grid-template-columns:minmax(180px,1fr) repeat(3,minmax(100px,1fr));
  }
  .footer-contact{ grid-column:1 / -1; }
}

/* 13. 移动端 */
@media (max-width:899px){
  html{ scroll-padding-top:132px; }
  .masthead__inner{
    grid-template-columns:1fr auto;
    grid-template-areas:
      "brand toggle"
      "cta cta";
    row-gap:12px;
    padding:14px var(--gutter);
  }
  .masthead__aside{ display:none; }
  .brand-lockup{ align-items:flex-start; text-align:left; padding-left:0; }
  .brand-tagline{ font-size:11px; letter-spacing:.12em; }
  .masthead__cta{ justify-self:stretch; }
  .masthead__cta .btn{ width:100%; }
  .nav-toggle{ display:inline-flex; }

  .site-nav{
    display:none;
    border-top:1px solid var(--line-mid);
    background:var(--space-800);
  }
  .site-nav[data-open]{ display:block; }
  .site-nav__list{
    flex-direction:column;
    flex-wrap:nowrap;
    justify-content:flex-start;
    gap:0;
    padding:6px 0 16px;
  }
  .site-nav__item{ border-bottom:1px solid rgba(124,120,153,.16); }
  .site-nav__item:last-child{ border-bottom:0; }
  .site-nav__link{
    display:block;
    padding:14px var(--gutter);
    font-size:16px;
  }
  .site-nav__link::after{ display:none; }
  .site-nav__link[aria-current="page"]{
    background:rgba(53,224,207,.08);
    border-left:2px solid var(--amber);
  }

  .grid--2,.grid--3,.split,.rail{ grid-template-columns:1fr; }
  .rail__aside{ position:static; top:auto; }

  .site-footer__top{
    grid-template-columns:repeat(2,minmax(0,1fr));
    gap:28px;
  }
  .footer-brand-block{ grid-column:1 / -1; }
  .footer-contact{ grid-column:1 / -1; }
  .site-footer__legal{ flex-direction:column; align-items:flex-start; }
}

@media (max-width:719px){
  .header-meta{ display:none; }
}

@media (max-width:419px){
  .site-footer__top{ grid-template-columns:1fr; }
  .brand-tagline{ letter-spacing:.06em; }
}

/* 14. 减少动效 */
@media (prefers-reduced-motion: reduce){
  html{ scroll-behavior:auto; }
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  .btn:hover{ transform:none; }
  .to-top{ transition:none; }
  .scroll-progress__bar{ transition:none; }
}