/* ==========================================================================
   半岛体育 · 共享样式表 /assets/site.css
   戈壁暮色 · 草皮绿 · 夜赛灯光橙 · 沙砾米白 · 天山蓝
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*,*::before,*::after{box-sizing:border-box}
html{
  -webkit-text-size-adjust:100%;
  text-size-adjust:100%;
  scroll-behavior:smooth;
}
body,h1,h2,h3,h4,h5,h6,p,ul,ol,li,figure,blockquote,dl,dt,dd{margin:0;padding:0}
ul,ol{list-style:none}
img,picture,svg,video{display:block;max-width:100%;height:auto}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;padding:0;cursor:pointer}
a{color:inherit;text-decoration:none}
table{border-collapse:collapse;width:100%}
:target{scroll-margin-top:150px}

/* ---------- 2. 设计变量 ---------- */
:root{
  --ink:#1B1712;
  --ink-2:#2E2A23;
  --pitch:#2F8F4E;
  --pitch-deep:#1F6B39;
  --flood:#F2792B;
  --sand:#F4EDE2;
  --sand-lift:#FBF7F0;
  --sky:#2C6E9B;
  --stone:#6B6259;
  --glass:rgba(244,237,226,.86);
  --on-dark:rgba(244,237,226,.82);
  --on-dark-soft:rgba(244,237,226,.62);
  --line:rgba(107,98,89,.30);
  --line-soft:rgba(107,98,89,.15);
  --line-ink:rgba(27,23,18,.18);
  --line-dark:rgba(244,237,226,.18);
  --font-display:"Noto Sans SC","Source Han Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --font-body:var(--font-display);
  --font-mono:"JetBrains Mono","IBM Plex Mono","Roboto Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --w:1200px;
  --gut:20px;
  --r-sm:3px;
  --r-md:6px;
  --r-lg:12px;
  --shadow-1:0 1px 0 rgba(27,23,18,.05),0 14px 28px -22px rgba(27,23,18,.55);
  --ease:cubic-bezier(.22,.61,.36,1);
}

/* ---------- 3. 基础中文排版 ---------- */
body{
  background-color:var(--sand);
  background-image:linear-gradient(90deg,rgba(107,98,89,.065) 1px,transparent 1px);
  background-size:96px 100%;
  color:var(--ink);
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
h1,h2,h3,h4,h5{
  font-family:var(--font-display);
  font-weight:900;
  line-height:1.18;
  letter-spacing:-.005em;
  color:var(--ink);
}
h1{font-size:clamp(2rem,5.2vw,3.4rem);letter-spacing:-.022em}
h2{font-size:clamp(1.5rem,3.2vw,2.3rem);letter-spacing:-.015em}
h3{font-size:clamp(1.15rem,2vw,1.45rem);font-weight:800}
h4{font-size:1.05rem;font-weight:800}
h5{font-size:.95rem;font-weight:800}
strong,b{font-weight:800}
small{font-size:.82rem}
::selection{background:var(--pitch);color:var(--sand-lift)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums;letter-spacing:-.01em}
#main-content{display:block;scroll-margin-top:150px;outline:none}

/* ---------- 4. 无障碍 ---------- */
.skip-link{
  position:fixed;
  top:10px;
  left:50%;
  z-index:300;
  transform:translate(-50%,-180%);
  padding:10px 20px;
  background:var(--ink);
  color:var(--sand-lift);
  font-weight:800;
  font-size:.9rem;
  border-radius:2px;
  border:1px solid var(--pitch);
  transition:transform .18s var(--ease);
}
.skip-link:focus{transform:translate(-50%,0)}
.visually-hidden{
  position:absolute!important;
  width:1px;height:1px;
  padding:0;margin:-1px;
  overflow:hidden;
  clip:rect(0 0 0 0);
  clip-path:inset(50%);
  white-space:nowrap;
  border:0;
}
:focus-visible{
  outline:3px solid var(--flood);
  outline-offset:2px;
  border-radius:2px;
}
.band-dark :focus-visible,
.site-footer :focus-visible,
.band-pitch :focus-visible{outline-color:var(--sand-lift)}

/* ---------- 5. 布局容器与区块 ---------- */
.container{
  width:100%;
  max-width:var(--w);
  margin:0 auto;
  padding-inline:var(--gut);
}
.section{padding-block:clamp(40px,6vw,88px)}
.section--tight{padding-block:clamp(24px,3.4vw,48px)}
.band{padding-block:clamp(40px,6vw,88px)}
.band--flush{padding-block:0}
.band-lift{background:var(--sand-lift);border-block:1px solid var(--line-soft)}
.band-dark{background:var(--ink);color:var(--on-dark)}
.band-dark h1,.band-dark h2,.band-dark h3,.band-dark h4{color:var(--sand-lift)}
.band-pitch{background:linear-gradient(135deg,var(--pitch-deep),var(--pitch));color:var(--sand-lift)}
.band-pitch h1,.band-pitch h2,.band-pitch h3{color:var(--sand-lift)}
.band-grid{
  background-image:
    linear-gradient(rgba(107,98,89,.09) 1px,transparent 1px),
    linear-gradient(90deg,rgba(107,98,89,.09) 1px,transparent 1px);
  background-size:56px 56px;
}
.divider{height:1px;border:0;background:var(--line);margin-block:clamp(24px,4vw,48px)}

/* ---------- 6. 正文与文字件 ---------- */
.prose{max-width:38em}
.prose p{max-width:38em;margin-bottom:1.1em}
.prose p:last-child{margin-bottom:0}
.prose h2{margin:1.6em 0 .6em}
.prose h3{margin:1.4em 0 .5em}
.lede{
  font-size:clamp(1.02rem,1.6vw,1.18rem);
  line-height:1.72;
  color:var(--ink-2);
  max-width:36em;
}
.band-dark .lede,.band-pitch .lede{color:rgba(244,237,226,.88)}
.note{
  font-size:.82rem;
  line-height:1.7;
  color:var(--stone);
  letter-spacing:.01em;
}
.band-dark .note,.site-footer .note{color:var(--on-dark-soft)}

/* ---------- 7. 章节头与展览标签 ---------- */
.section-head{
  display:flex;
  flex-wrap:wrap;
  align-items:baseline;
  gap:12px 22px;
  margin-bottom:clamp(20px,3vw,36px);
  padding-bottom:14px;
  border-bottom:1px solid var(--line);
}
.section-head h2,.section-head h3{margin:0}
.section-label{
  display:inline-flex;
  align-items:center;
  gap:9px;
  font-size:.76rem;
  font-weight:800;
  letter-spacing:.16em;
  color:var(--stone);
  flex:0 0 auto;
}
.section-label::before{
  content:"";
  width:13px;
  height:13px;
  background:var(--pitch);
  flex:0 0 auto;
}
.section-label--flood::before{background:var(--flood)}
.section-label--sky::before{background:var(--sky)}
.band-dark .section-label{color:var(--on-dark-soft)}
.section-note{
  margin-left:auto;
  font-size:.78rem;
  letter-spacing:.08em;
  color:var(--stone);
  font-family:var(--font-mono);
}
.band-dark .section-note{color:var(--on-dark-soft)}

/* ---------- 8. 按钮 ---------- */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:10px 18px;
  border:1px solid transparent;
  border-radius:2px;
  font-size:.9rem;
  font-weight:800;
  letter-spacing:.03em;
  line-height:1.2;
  white-space:nowrap;
  transition:background-color .18s var(--ease),color .18s var(--ease),border-color .18s var(--ease);
}
.btn-accent{background:var(--flood);color:#20140A}
.btn-accent:hover{background:#FF9046}
.btn-pitch{background:var(--pitch);color:var(--sand-lift)}
.btn-pitch:hover{background:var(--pitch-deep)}
.btn-ghost{border-color:var(--line);color:var(--ink);background:rgba(251,247,240,.5)}
.btn-ghost:hover{background:var(--ink);color:var(--sand-lift);border-color:var(--ink)}
.band-dark .btn-ghost,.band-pitch .btn-ghost{
  border-color:rgba(244,237,226,.42);
  color:var(--sand-lift);
  background:rgba(244,237,226,.06);
}
.band-dark .btn-ghost:hover,.band-pitch .btn-ghost:hover{background:var(--sand-lift);color:var(--ink)}

/* ---------- 9. 网格 ---------- */
.grid{display:grid;gap:clamp(16px,2.4vw,28px)}
.grid-2{grid-template-columns:repeat(auto-fit,minmax(260px,1fr))}
.grid-3{grid-template-columns:repeat(auto-fit,minmax(216px,1fr))}
.grid-aside{display:grid;gap:clamp(24px,4vw,48px);grid-template-columns:minmax(0,1fr)}
.grid-aside-main{min-width:0}
.grid-aside-side{min-width:0}
@media (min-width:960px){
  .grid-aside{grid-template-columns:minmax(0,1fr) 290px}
  .grid-aside-side{position:sticky;top:150px;align-self:start}
}

/* ---------- 10. 卡片 ---------- */
.card{
  display:block;
  background:var(--sand-lift);
  border:1px solid var(--line);
  border-radius:var(--r-md);
  padding:20px 22px;
  transition:transform .2s var(--ease),border-color .2s var(--ease),box-shadow .2s var(--ease);
}
.card:hover{transform:translateY(-2px);border-color:var(--pitch);box-shadow:var(--shadow-1)}
.card--dark{
  background:var(--ink-2);
  border-color:var(--line-dark);
  color:var(--on-dark);
}
.card--dark:hover{border-color:var(--pitch)}
.band-dark .card{background:rgba(244,237,226,.06);border-color:var(--line-dark);color:var(--on-dark)}
.band-dark .card:hover{background:rgba(244,237,226,.1);border-color:var(--pitch)}
.card-title{font-size:1.05rem;font-weight:800;margin-bottom:8px}
.card-meta{font-size:.78rem;letter-spacing:.08em;color:var(--stone);font-family:var(--font-mono)}

/* ---------- 11. 标签 ---------- */
.tag-row{display:flex;flex-wrap:wrap;gap:8px}
.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:3px 10px;
  font-size:.74rem;
  font-weight:700;
  letter-spacing:.08em;
  border:1px solid var(--line);
  border-radius:2px;
  color:var(--stone);
  background:var(--sand-lift);
}
.tag--pitch{background:rgba(47,143,78,.12);border-color:rgba(47,143,78,.42);color:var(--pitch-deep)}
.tag--flood{background:rgba(242,121,43,.14);border-color:rgba(242,121,43,.45);color:#A94E10}
.tag--ocean{background:rgba(44,110,155,.12);border-color:rgba(44,110,155,.4);color:#1F5578}
.tag--stone{background:rgba(107,98,89,.1);border-color:var(--line);color:var(--stone)}

/* ---------- 12. 数据锚点 ---------- */
.stat-row{
  display:grid;
  gap:clamp(18px,3vw,40px);
  grid-template-columns:repeat(auto-fit,minmax(150px,1fr));
}
.stat{display:grid;gap:6px;border-left:3px solid var(--pitch);padding-left:16px}
.stat--flood{border-left-color:var(--flood)}
.stat--sky{border-left-color:var(--sky)}
.stat-num{
  font-family:var(--font-mono);
  font-variant-numeric:tabular-nums;
  font-weight:700;
  font-size:clamp(1.9rem,4.8vw,3rem);
  line-height:1;
  letter-spacing:-.03em;
  color:var(--pitch-deep);
}
.stat--flood .stat-num{color:#C25A15}
.stat--sky .stat-num{color:var(--sky)}
.stat-label{font-size:.78rem;letter-spacing:.14em;color:var(--stone)}
.band-dark .stat-num{color:var(--sand-lift)}
.band-dark .stat-label{color:var(--on-dark-soft)}

/* ---------- 13. 列表与时间轴 ---------- */
.list-plain{display:grid;gap:12px}
.list-plain li{position:relative;padding-left:20px;line-height:1.75}
.list-plain li::before{
  content:"";
  position:absolute;
  left:0;
  top:.72em;
  width:9px;
  height:2px;
  background:var(--pitch);
}
.band-dark .list-plain li::before{background:var(--flood)}
.timeline{position:relative;display:grid;gap:20px;padding-left:24px}
.timeline::before{
  content:"";
  position:absolute;
  left:5px;
  top:8px;
  bottom:8px;
  width:2px;
  background:linear-gradient(180deg,var(--pitch),rgba(47,143,78,.12));
}
.timeline-item{position:relative}
.timeline-item::before{
  content:"";
  position:absolute;
  left:-24px;
  top:7px;
  width:12px;
  height:12px;
  border-radius:50%;
  background:var(--sand);
  border:3px solid var(--pitch);
}
.timeline-time{
  display:block;
  font-family:var(--font-mono);
  font-size:.8rem;
  letter-spacing:.04em;
  color:var(--stone);
}
.band-dark .timeline-item::before{background:var(--ink);border-color:var(--flood)}
.band-dark .timeline-time{color:var(--on-dark-soft)}

/* ---------- 14. 图片容器 ---------- */
.media-frame{
  position:relative;
  display:block;
  overflow:hidden;
  border-radius:var(--r-md);
  border:1px solid var(--line);
  background:var(--ink-2);
  aspect-ratio:4/3;
}
.media-frame img,
.media-frame picture,
.media-frame video{
  width:100%;
  height:100%;
  object-fit:cover;
}
.media-frame::after{
  content:"";
  position:absolute;
  inset:auto 0 0 0;
  height:46%;
  background:linear-gradient(180deg,rgba(27,23,18,0) 0%,rgba(27,23,18,.68) 100%);
  pointer-events:none;
}
.media-frame--wide{aspect-ratio:16/9}
.media-frame--panorama{aspect-ratio:21/9}
.media-frame--tall{aspect-ratio:3/4}
.media-frame--square{aspect-ratio:1/1}
.media-frame-placeholder{
  position:absolute;
  inset:0;
  background:
    linear-gradient(rgba(244,237,226,.07) 1px,transparent 1px) 0 0/40px 40px,
    linear-gradient(90deg,rgba(244,237,226,.07) 1px,transparent 1px) 0 0/40px 40px,
    linear-gradient(140deg,#2E2A23 0%,#1B1712 52%,rgba(47,143,78,.5) 100%);
}
.media-frame figcaption{
  position:absolute;
  left:16px;
  right:16px;
  bottom:14px;
  z-index:2;
  font-size:.78rem;
  letter-spacing:.06em;
  color:rgba(244,237,226,.86);
}
@media (max-width:640px){
  .media-frame--panorama{aspect-ratio:16/9}
}

/* ---------- 15. 面包屑与章节目录 ---------- */
.breadcrumb{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:6px;
  font-size:.78rem;
  letter-spacing:.06em;
  color:var(--stone);
}
.breadcrumb li{display:inline-flex;align-items:center;gap:6px}
.breadcrumb li+li::before{content:"/";color:var(--line);margin-right:2px}
.breadcrumb a:hover{color:var(--pitch-deep)}
.toc{display:grid;gap:6px;font-size:.86rem}
@media (min-width:960px){.toc{position:sticky;top:150px}}
.toc-title{
  font-size:.74rem;
  letter-spacing:.16em;
  font-weight:800;
  color:var(--stone);
  margin-bottom:4px;
}
.toc-link{
  display:block;
  padding:6px 0 6px 13px;
  border-left:2px solid var(--line);
  color:var(--stone);
  line-height:1.5;
  transition:color .18s var(--ease),border-color .18s var(--ease);
}
.toc-link:hover{color:var(--ink)}
.toc-link[aria-current]{color:var(--ink);font-weight:800;border-left-color:var(--flood)}
[data-chapter]{scroll-margin-top:150px}

/* ---------- 16. 页头 ---------- */
.site-header{
  position:sticky;
  top:0;
  z-index:90;
  background:var(--glass);
  backdrop-filter:blur(14px);
  -webkit-backdrop-filter:blur(14px);
  box-shadow:0 1px 0 var(--line-ink),0 18px 30px -30px rgba(27,23,18,.95);
}
.header-bar{transition:background-color .2s var(--ease)}
.header-inner{
  display:grid;
  grid-template-columns:1fr auto 1fr;
  align-items:center;
  gap:18px;
  width:100%;
  max-width:var(--w);
  margin:0 auto;
  padding:14px var(--gut);
  transition:padding .24s var(--ease);
}
.header-rail{
  display:flex;
  align-items:center;
  gap:10px;
  justify-self:start;
  min-width:0;
}
.rail-label{font-size:.72rem;letter-spacing:.16em;color:var(--stone)}
.rail-num{
  font-weight:700;
  font-size:1rem;
  color:var(--ink);
  background:var(--sand-lift);
  border:1px solid var(--line);
  padding:1px 8px;
  border-radius:2px;
}
.rail-pill{
  font-size:.76rem;
  letter-spacing:.06em;
  color:var(--stone);
  border:1px solid var(--line);
  padding:3px 10px;
  border-radius:2px;
  transition:color .18s var(--ease),border-color .18s var(--ease),background-color .18s var(--ease);
}
.rail-pill:hover{color:var(--ink);border-color:var(--pitch);background:rgba(47,143,78,.1)}
.masthead{text-align:center;min-width:0}
.brand{display:inline-flex;align-items:center;gap:11px}
.brand-mark{
  position:relative;
  display:inline-block;
  width:13px;
  height:13px;
  background:var(--pitch);
  border-radius:1px;
  flex:0 0 auto;
}
.brand-mark::after{
  content:"";
  position:absolute;
  left:0;
  bottom:-6px;
  width:13px;
  height:3px;
  background:var(--flood);
}
.brand-name{
  font-family:var(--font-display);
  font-weight:900;
  font-size:clamp(1.5rem,3.3vw,2.3rem);
  line-height:1;
  letter-spacing:.04em;
  color:var(--ink);
  transition:font-size .24s var(--ease);
}
.brand-tagline{
  margin-top:8px;
  font-size:.74rem;
  letter-spacing:.18em;
  color:var(--stone);
}
.header-utility{
  display:flex;
  align-items:center;
  gap:10px;
  justify-self:end;
}
.util-link{
  display:inline-flex;
  align-items:center;
  padding:8px 12px;
  border:1px solid transparent;
  border-radius:2px;
  font-size:.86rem;
  font-weight:700;
  letter-spacing:.04em;
  color:var(--ink);
  transition:border-color .18s var(--ease),background-color .18s var(--ease);
}
.util-link:hover{border-color:var(--line);background:var(--sand-lift)}
.nav-toggle{
  display:none;
  flex-direction:column;
  align-items:center;
  justify-content:center;
  gap:4px;
  width:52px;
  height:44px;
  border:1px solid var(--line-ink);
  border-radius:2px;
  background:var(--sand-lift);
  justify-self:end;
  transition:border-color .18s var(--ease);
}
.nav-toggle:hover{border-color:var(--pitch)}
.nav-toggle-bar{
  display:block;
  width:20px;
  height:2px;
  background:var(--ink);
  transition:transform .2s var(--ease),opacity .2s var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1){transform:translateY(6px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3){transform:translateY(-6px) rotate(-45deg)}
.primary-nav{
  display:block;
  background:var(--ink);
  border-top:1px solid rgba(244,237,226,.08);
}
.nav-list{
  display:flex;
  flex-wrap:wrap;
  gap:2px;
  max-width:var(--w);
  margin:0 auto;
  padding-inline:var(--gut);
}
.nav-link{
  display:block;
  padding:11px 15px;
  color:rgba(244,237,226,.76);
  font-size:.92rem;
  font-weight:700;
  letter-spacing:.06em;
  border-bottom:3px solid transparent;
  transition:color .18s var(--ease),background-color .18s var(--ease),border-color .18s var(--ease),padding .24s var(--ease);
}
.nav-link:hover{color:var(--sand-lift);background:rgba(244,237,226,.08)}
.nav-link[aria-current="page"]{
  color:var(--sand-lift);
  border-bottom-color:var(--pitch);
  background:rgba(47,143,78,.2);
}
.scroll-progress{
  position:absolute;
  left:0;
  bottom:0;
  width:100%;
  height:3px;
  background:linear-gradient(90deg,var(--pitch) 0%,var(--flood) 100%);
  transform:scaleX(0);
  transform-origin:0 50%;
  will-change:transform;
}
/* 吸顶收缩态 */
.site-header[data-stuck] .header-inner{padding-block:8px}
.site-header[data-stuck] .brand-name{font-size:1.3rem}
.site-header[data-stuck] .brand-tagline{display:none}
.site-header[data-stuck] .nav-link{padding-block:9px}

/* ---------- 17. 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:clamp(48px,7vw,96px);
  background:var(--ink);
  color:var(--on-dark);
}
.site-footer::before{
  content:"";
  position:absolute;
  inset:0 0 auto 0;
  height:4px;
  background:linear-gradient(90deg,var(--pitch) 0 58%,var(--flood) 58% 100%);
}
.footer-inner{
  width:100%;
  max-width:var(--w);
  margin:0 auto;
  padding:clamp(40px,5.4vw,72px) var(--gut) 28px;
}
.footer-grid{
  display:grid;
  gap:clamp(26px,4vw,56px);
  grid-template-columns:minmax(0,1.5fr) repeat(3,minmax(0,1fr));
}
.footer-brand .brand-name{color:var(--sand-lift);font-size:1.6rem}
.footer-brand .brand-mark{background:var(--pitch)}
.footer-tagline{
  margin-top:12px;
  font-size:.78rem;
  letter-spacing:.16em;
  color:var(--on-dark-soft);
}
.footer-blurb{
  margin-top:14px;
  max-width:34em;
  font-size:.92rem;
  line-height:1.8;
  color:rgba(244,237,226,.72);
}
.footer-col-title{
  display:flex;
  align-items:center;
  gap:9px;
  margin-bottom:16px;
  font-size:.78rem;
  font-weight:800;
  letter-spacing:.18em;
  color:var(--sand-lift);
}
.footer-col-title::before{
  content:"";
  width:9px;
  height:9px;
  background:var(--pitch);
  flex:0 0 auto;
}
.footer-list{display:grid;gap:10px}
.footer-link{
  display:inline-block;
  font-size:.92rem;
  color:rgba(244,237,226,.76);
  border-bottom:1px solid transparent;
  transition:color .18s var(--ease),border-color .18s var(--ease);
}
.footer-link:hover{color:var(--sand-lift);border-bottom-color:var(--flood)}
.footer-contact{
  display:flex;
  flex-wrap:wrap;
  gap:10px 32px;
  margin-top:clamp(28px,4vw,44px);
  padding-top:22px;
  border-top:1px solid var(--line-dark);
  font-size:.88rem;
  color:rgba(244,237,226,.78);
}
.footer-contact-label{
  display:inline-block;
  margin-right:8px;
  font-size:.72rem;
  letter-spacing:.14em;
  color:var(--flood);
}
.footer-address{
  margin-top:12px;
  font-size:.86rem;
  color:var(--on-dark-soft);
}
.footer-bottom{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:10px 24px;
  margin-top:22px;
  padding-top:18px;
  border-top:1px solid var(--line-dark);
  font-size:.78rem;
  letter-spacing:.04em;
  color:var(--on-dark-soft);
}
.footer-legal{font-family:var(--font-mono);letter-spacing:.08em}
.footer-note{color:var(--on-dark-soft)}
.footer-copy{font-family:var(--font-mono)}

/* ---------- 18. 返回顶部 ---------- */
.back-to-top{
  position:fixed;
  right:18px;
  bottom:22px;
  z-index:120;
  display:none;
  align-items:center;
  gap:8px;
  padding:10px 15px;
  background:var(--ink);
  color:var(--sand-lift);
  border:1px solid rgba(244,237,226,.3);
  border-radius:2px;
  font-size:.78rem;
  font-weight:800;
  letter-spacing:.14em;
  box-shadow:0 14px 28px -20px rgba(0,0,0,.95);
  transition:background-color .18s var(--ease),border-color .18s var(--ease);
}
.back-to-top[data-visible="true"]{display:inline-flex}
.back-to-top:hover{background:var(--pitch-deep);border-color:var(--pitch)}
.back-to-top-icon{font-family:var(--font-mono);font-size:.95rem;line-height:1}

/* ---------- 19. 动效 ---------- */
.js [data-reveal]{
  opacity:0;
  transform:translateY(14px);
  transition:opacity .44s var(--ease),transform .44s var(--ease);
}
.js [data-reveal].is-visible{opacity:1;transform:none}

/* ---------- 20. 响应式 ---------- */
@media (max-width:1079px){
  .header-rail{display:none}
  .header-inner{grid-template-columns:minmax(0,1fr) auto}
  .masthead{text-align:left}
}
@media (max-width:899px){
  .header-inner{
    grid-template-columns:minmax(0,1fr) auto auto;
    gap:8px;
    padding:10px var(--gut);
  }
  .util-link{display:none}
  .nav-toggle{display:inline-flex}
  .brand-tagline{display:none}
  .primary-nav{display:none}
  .primary-nav[data-open]{display:block}
  .nav-list{flex-direction:column;gap:0;padding:8px var(--gut) 16px}
  .nav-link{
    border-bottom:1px solid var(--line-dark);
    border-left:3px solid transparent;
    padding:13px 12px;
    font-size:.95rem;
  }
  .nav-link:hover{background:rgba(244,237,226,.06)}
  .nav-link[aria-current="page"]{
    border-bottom-color:var(--line-dark);
    border-left-color:var(--pitch);
    background:rgba(47,143,78,.18);
  }
  .site-header[data-stuck] .brand-name{font-size:1.15rem}
  .site-header[data-stuck] .nav-link{padding-block:13px}
  .footer-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .footer-brand{grid-column:1 / -1}
  .footer-bottom{justify-content:flex-start}
}
@media (max-width:640px){
  :root{--gut:16px}
  .header-utility .btn{padding:9px 12px;font-size:.82rem}
  .footer-inner{padding-top:34px}
  .back-to-top{right:12px;bottom:14px;padding:9px 12px}
  .back-to-top-text{display:none}
  .grid-3{grid-template-columns:minmax(0,1fr)}
}
@media (max-width:560px){
  .header-utility .btn{display:none}
  .footer-grid{grid-template-columns:minmax(0,1fr)}
}

/* ---------- 21. 减弱动效 ---------- */
@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;
  }
  .js [data-reveal]{opacity:1;transform:none;transition:none}
  .card:hover{transform:none}
}