/* ==========================================================================
   reach-boyu.com.cn — Site Kit shared stylesheet (/assets/site.css)
   水下竞技场：深海底 + 泳道线 + 切角面板 + 纸感内容带
   ========================================================================== */

/* ---------- 1. reset ---------- */
*,*::before,*::after{box-sizing:border-box}

html{
  -webkit-text-size-adjust:100%;
  scroll-behavior:smooth;
  scroll-padding-top:calc(var(--header-h) + 18px);
}

body{
  margin:0;
  background:var(--abyss);
  color:var(--frost);
  font-family:var(--font-body);
  font-size:17px;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

h1,h2,h3,h4,h5,h6,p,figure,figcaption,blockquote{margin:0}
ul,ol{margin:0;padding:0;list-style:none}
img,picture,video,svg{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
table{border-collapse:collapse;width:100%}

:focus-visible{outline:2px solid var(--neon);outline-offset:3px}
::selection{background:var(--neon);color:var(--abyss)}

/* ---------- 2. tokens ---------- */
:root{
  --abyss:#04222B;
  --deep-teal:#083B47;
  --mid-teal:#0F5A66;
  --parchment:#F4EBDC;
  --sand:#E4D4BB;
  --ink:#221812;
  --frost:#F5F1E8;
  --neon:#35E6D0;
  --orange:#FF5A1F;
  --gold:#E8B34A;
  --aqua:#9BDDE6;
  --slate:#4A6B72;

  --shell:1240px;
  --gutter:clamp(18px,4vw,56px);
  --header-h:72px;
  --lane:rgba(53,230,208,.16);
  --lane-strong:rgba(53,230,208,.42);

  --font-body:"PingFang SC","Hiragino Sans GB","Source Han Sans SC","Noto Sans SC","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --font-display:"Barlow Condensed","Oswald","Helvetica Neue Condensed","Arial Narrow","PingFang SC","Microsoft YaHei",sans-serif;
  --font-mono:"IBM Plex Mono","SFMono-Regular",ui-monospace,Menlo,Consolas,"Courier New",monospace;

  --ease:cubic-bezier(.2,.7,.3,1);
  --cut:14px;
}

/* ---------- 3. 全局水光与颗粒 ---------- */
body::before{
  content:"";
  position:fixed;
  inset:0;
  z-index:60;
  pointer-events:none;
  opacity:.04;
  background-image:radial-gradient(rgba(245,241,232,.85) .5px,transparent .6px);
  background-size:3px 3px;
  mix-blend-mode:screen;
}

body.nav-open{overflow:hidden}

/* ---------- 4. skip link ---------- */
.skip-link{
  position:absolute;
  left:50%;
  top:-64px;
  transform:translateX(-50%);
  z-index:120;
  padding:10px 22px;
  background:var(--neon);
  color:var(--abyss);
  font-size:14px;
  font-weight:800;
  letter-spacing:.04em;
  border-radius:0 0 2px 2px;
  transition:top .18s var(--ease);
}
.skip-link:focus{top:0}

/* ---------- 5. header ---------- */
.site-header{
  position:sticky;
  top:0;
  z-index:80;
  background:#04222B;
  border-bottom:1px solid var(--lane);
}

.header-inner{
  position:relative;
  max-width:var(--shell);
  margin-inline:auto;
  padding-inline:var(--gutter);
  height:var(--header-h);
  display:flex;
  align-items:center;
  gap:clamp(14px,2.4vw,36px);
}

/* 品牌 */
.brand{flex:0 0 auto;min-width:0}
.brand-link{
  display:flex;
  align-items:center;
  gap:12px;
  padding:6px 0;
}
.brand-mark{
  position:relative;
  flex:0 0 auto;
  width:32px;
  height:32px;
  background:var(--orange);
  clip-path:polygon(0 0,100% 0,100% 64%,64% 100%,0 100%);
}
.brand-mark::before{
  content:"";
  position:absolute;
  left:7px;
  right:7px;
  top:50%;
  height:1.5px;
  background:var(--abyss);
  box-shadow:0 5px 0 var(--abyss),0 -5px 0 var(--abyss);
  transform:translateY(-50%) skewX(-14deg);
}
.brand-text{display:flex;flex-direction:column;min-width:0}
.brand-cn{
  font-weight:800;
  font-size:18px;
  line-height:1.25;
  letter-spacing:.06em;
  color:var(--frost);
}
.brand-en{
  font-family:var(--font-display);
  font-size:10px;
  line-height:1.3;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--aqua);
  white-space:nowrap;
}

/* 水道式留白 */
.lane-gap{
  flex:1 1 auto;
  display:flex;
  flex-direction:column;
  justify-content:center;
  gap:5px;
  height:24px;
  min-width:40px;
  opacity:.7;
}
.lane-gap span{
  display:block;
  height:1px;
  background:linear-gradient(90deg,transparent,var(--mid-teal) 18%,var(--neon) 50%,var(--mid-teal) 82%,transparent);
  transform:skewX(-24deg);
}
.lane-gap span:nth-child(1){width:100%}
.lane-gap span:nth-child(2){width:88%;margin-left:6%}
.lane-gap span:nth-child(3){width:72%;margin-left:14%}

/* 导航 */
.site-nav{
  display:flex;
  flex-direction:column;
  align-items:flex-end;
  flex:0 0 auto;
}
.nav-list{
  display:flex;
  align-items:center;
  gap:clamp(8px,1.5vw,24px);
}
.nav-item{position:relative}
.nav-link{
  position:relative;
  display:flex;
  align-items:baseline;
  gap:6px;
  padding:12px 2px 10px;
  font-size:14.5px;
  letter-spacing:.02em;
  color:rgba(245,241,232,.76);
  transition:color .18s var(--ease);
}
.nav-link::after{
  content:"";
  position:absolute;
  left:0;
  right:100%;
  bottom:2px;
  height:2px;
  background:var(--neon);
  transition:right .2s var(--ease);
}
.nav-num{
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.06em;
  color:var(--slate);
  transition:color .18s var(--ease);
}
.nav-label{white-space:nowrap}
.nav-desc{display:none}
.nav-link:hover{color:var(--frost)}
.nav-link:hover::after{right:0}
.nav-link:hover .nav-num{color:var(--neon)}
.nav-link[aria-current="page"]{color:var(--frost);font-weight:700}
.nav-link[aria-current="page"]::after{right:0}
.nav-link[aria-current="page"] .nav-num{color:var(--orange)}
.nav-meta{
  display:none;
  margin-top:18px;
  padding-top:14px;
  border-top:1px solid var(--lane);
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.1em;
  color:var(--aqua);
}

/* 抽屉按钮 */
.nav-toggle{
  display:none;
  align-items:center;
  gap:9px;
  padding:10px 14px;
  border:1px solid var(--mid-teal);
  color:var(--frost);
  font-size:13px;
  letter-spacing:.08em;
  clip-path:polygon(0 0,calc(100% - 10px) 0,100% 10px,100% 100%,10px 100%,0 calc(100% - 10px));
  transition:border-color .18s var(--ease),color .18s var(--ease);
}
.nav-toggle:hover{border-color:var(--neon);color:var(--neon)}
.nav-toggle-bars{
  display:flex;
  flex-direction:column;
  justify-content:center;
  gap:4px;
  width:22px;
  height:14px;
}
.nav-toggle-bars i{
  display:block;
  height:1.5px;
  width:100%;
  background:currentColor;
  transition:transform .2s var(--ease),opacity .2s var(--ease);
}
.nav-toggle-text{white-space:nowrap}

.site-header[data-open] .nav-toggle-bars i:nth-child(1){transform:translateY(5.5px) rotate(45deg)}
.site-header[data-open] .nav-toggle-bars i:nth-child(2){opacity:0}
.site-header[data-open] .nav-toggle-bars i:nth-child(3){transform:translateY(-5.5px) rotate(-45deg)}

/* 遮罩 */
.nav-scrim{
  display:none;
  position:fixed;
  inset:0;
  z-index:1;
  background:rgba(4,34,43,.68);
  opacity:0;
  pointer-events:none;
  transition:opacity .25s var(--ease);
}

/* 滚动进度 */
.scroll-progress{
  position:absolute;
  left:0;
  bottom:-1px;
  width:100%;
  height:2px;
  background:linear-gradient(90deg,var(--neon),var(--orange));
  transform:scaleX(0);
  transform-origin:0 50%;
  transition:transform .08s linear;
}

/* ---------- 6. 容器与栅格 ---------- */
.shell{
  width:100%;
  max-width:var(--shell);
  margin-inline:auto;
  padding-inline:var(--gutter);
}

.grid12{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:clamp(14px,2.2vw,28px);
}
.col-2{grid-column:span 2}
.col-3{grid-column:span 3}
.col-4{grid-column:span 4}
.col-5{grid-column:span 5}
.col-6{grid-column:span 6}
.col-7{grid-column:span 7}
.col-8{grid-column:span 8}
.col-9{grid-column:span 9}
.col-10{grid-column:span 10}
.col-12{grid-column:span 12}

/* ---------- 7. 分区与标题组 ---------- */
.section{
  position:relative;
  padding-block:clamp(40px,7vw,96px);
}
.section--dark{background:var(--abyss);color:var(--frost)}
.section--teal{background:var(--deep-teal);color:var(--frost)}
.section--paper{background:var(--parchment);color:var(--ink)}
.section--paper a{color:#0F5A66}
.section--paper a:hover{color:var(--orange)}

.section-head{
  display:flex;
  flex-wrap:wrap;
  align-items:flex-end;
  justify-content:space-between;
  gap:18px 32px;
  margin-bottom:clamp(22px,3.4vw,44px);
}
.section-head__body{max-width:38em}

.eyebrow{
  display:inline-flex;
  align-items:center;
  gap:10px;
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.24em;
  text-transform:uppercase;
  color:var(--neon);
}
.eyebrow::before{
  content:"";
  width:26px;
  height:1px;
  background:currentColor;
  transform:skewX(-30deg);
}
.section--paper .eyebrow{color:#0F5A66}

.display{
  font-family:var(--font-display);
  font-weight:900;
  font-size:clamp(36px,6vw,84px);
  line-height:1.02;
  letter-spacing:-.02em;
  color:inherit;
  transform:skewX(-3deg);
  transform-origin:left bottom;
}
.display--sm{font-size:clamp(28px,3.6vw,48px)}

.lede{
  margin-top:14px;
  max-width:38em;
  font-size:clamp(15px,1.15vw,18px);
  line-height:1.78;
  color:rgba(245,241,232,.82);
}
.section--paper .lede{color:#3A2B22}

.side-note{
  writing-mode:vertical-rl;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.26em;
  text-transform:uppercase;
  color:var(--aqua);
}

/* ---------- 8. 按钮 ---------- */
.btn{
  display:inline-flex;
  align-items:center;
  gap:10px;
  padding:14px 24px;
  font-family:var(--font-body);
  font-size:15px;
  font-weight:800;
  letter-spacing:.03em;
  line-height:1.2;
  border:1px solid transparent;
  border-radius:2px;
  clip-path:polygon(0 0,calc(100% - 12px) 0,100% 12px,100% 100%,12px 100%,0 calc(100% - 12px));
  transition:transform .18s var(--ease),background-color .18s var(--ease),color .18s var(--ease),border-color .18s var(--ease);
}
.btn:active{transform:scale(.98)}
.btn-primary{background:var(--orange);color:var(--abyss)}
.btn-primary:hover{background:#FF7A47}
.btn-ghost{
  border-color:var(--mid-teal);
  color:var(--frost);
  background:rgba(8,59,71,.4);
}
.btn-ghost:hover{border-color:var(--neon);color:var(--neon)}
.btn-arrow::after{
  content:"→";
  font-family:var(--font-mono);
  font-size:14px;
  transform:translateX(0);
  transition:transform .18s var(--ease);
}
.btn-arrow:hover::after{transform:translateX(3px)}

/* ---------- 9. 面包屑 ---------- */
.breadcrumbs{
  padding-block:18px 0;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  color:var(--aqua);
}
.breadcrumbs ol{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:6px;
}
.breadcrumbs li{display:flex;align-items:center;gap:6px}
.breadcrumbs li+li::before{content:"／";color:var(--slate)}
.breadcrumbs a{color:var(--aqua);border-bottom:1px solid transparent;transition:color .18s var(--ease),border-color .18s var(--ease)}
.breadcrumbs a:hover{color:var(--neon);border-bottom-color:var(--neon)}
.breadcrumbs [aria-current="page"]{color:var(--frost)}

/* ---------- 10. 目录行 ---------- */
.index-row{
  display:grid;
  grid-template-columns:auto minmax(0,1fr) auto auto;
  align-items:center;
  gap:clamp(10px,2vw,26px);
  padding:18px clamp(10px,1.6vw,22px);
  border-bottom:1px solid var(--lane);
  transition:background-color .18s var(--ease),transform .18s var(--ease),border-color .18s var(--ease);
}
.index-row:hover{
  background:rgba(53,230,208,.06);
  border-bottom-color:var(--lane-strong);
  transform:translateX(2px);
}
.index-num{
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.1em;
  color:var(--slate);
}
.index-row:hover .index-num{color:var(--orange)}
.index-title{
  display:block;
  font-size:clamp(16px,1.5vw,19px);
  font-weight:800;
  letter-spacing:.01em;
  color:inherit;
}
.index-desc{
  display:block;
  margin-top:2px;
  font-size:13px;
  line-height:1.6;
  color:rgba(155,221,230,.85);
}
.section--paper .index-desc{color:#5A4638}
.index-meta{
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.08em;
  color:var(--gold);
  white-space:nowrap;
}
.index-arrow{
  font-family:var(--font-mono);
  font-size:14px;
  color:var(--neon);
  transition:transform .18s var(--ease);
}
.index-row:hover .index-arrow{transform:translateX(4px)}

/* ---------- 11. 步骤条 ---------- */
.step-bar{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(150px,1fr));
  gap:1px;
  background:var(--lane);
  border:1px solid var(--lane);
}
.step-bar__item{
  position:relative;
  padding:16px 18px 18px;
  background:var(--abyss);
}
.step-bar__item::before{
  content:"";
  position:absolute;
  left:0;
  top:0;
  width:100%;
  height:2px;
  background:linear-gradient(90deg,var(--neon),transparent);
  transform:scaleX(0);
  transform-origin:0 50%;
  transition:transform .24s var(--ease);
}
.step-bar__item:hover::before,
.step-bar__item.is-active::before{transform:scaleX(1)}
.step-bar__num{
  display:block;
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.18em;
  color:var(--neon);
}
.step-bar__label{
  display:block;
  margin-top:6px;
  font-size:15.5px;
  font-weight:800;
}
.step-bar__note{
  display:block;
  margin-top:4px;
  font-size:12.5px;
  line-height:1.6;
  color:var(--aqua);
}

/* ---------- 12. 礼包卡 ---------- */
.gift-card{
  position:relative;
  padding:clamp(18px,2.2vw,26px);
  background:linear-gradient(150deg,var(--deep-teal),#062B34);
  border:1px solid var(--mid-teal);
  border-radius:2px;
  clip-path:polygon(0 0,calc(100% - var(--cut)) 0,100% var(--cut),100% 100%,0 100%);
  transition:transform .18s var(--ease),border-color .18s var(--ease);
}
.gift-card:hover{transform:translateY(-2px);border-color:var(--neon)}
.gift-card__badge{
  position:absolute;
  top:10px;
  right:12px;
  padding:2px 9px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.08em;
  color:var(--gold);
  background:rgba(232,179,74,.12);
  border:1px solid rgba(232,179,74,.55);
  border-radius:2px;
}
.gift-card__title{
  font-size:17px;
  font-weight:800;
  padding-right:64px;
}
.gift-card__text{
  margin-top:8px;
  font-size:13.5px;
  line-height:1.7;
  color:var(--aqua);
}
.gift-card__foot{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  margin-top:16px;
  padding-top:12px;
  border-top:1px solid var(--lane);
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.08em;
  color:var(--slate);
}

/* ---------- 13. 会员阶梯 ---------- */
.member-ladder{
  display:grid;
  grid-template-columns:repeat(5,minmax(0,1fr));
  align-items:end;
  gap:clamp(6px,1vw,14px);
  height:clamp(160px,22vw,220px);
}
.member-ladder__step{
  display:flex;
  flex-direction:column;
  justify-content:flex-end;
  gap:4px;
  padding:10px 8px;
  background:linear-gradient(180deg,var(--mid-teal),var(--deep-teal));
  border-top:2px solid var(--neon);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.06em;
  color:var(--frost);
  transition:background-color .18s var(--ease);
}
.member-ladder__step:hover{background:linear-gradient(180deg,#136C7A,var(--deep-teal))}
.member-ladder__step:nth-child(1){height:38%;border-top-color:var(--slate)}
.member-ladder__step:nth-child(2){height:54%}
.member-ladder__step:nth-child(3){height:70%;border-top-color:var(--aqua)}
.member-ladder__step:nth-child(4){height:86%;border-top-color:var(--gold)}
.member-ladder__step:nth-child(5){height:100%;border-top-color:var(--gold);background:linear-gradient(180deg,#1B7E8C,var(--deep-teal))}
.member-ladder__name{font-family:var(--font-body);font-size:12.5px;font-weight:800;letter-spacing:0}

/* ---------- 14. 标签 ---------- */
.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:5px 12px;
  font-size:12.5px;
  letter-spacing:.04em;
  color:var(--aqua);
  background:rgba(15,90,102,.3);
  border:1px solid var(--mid-teal);
  border-radius:999px;
  transition:color .18s var(--ease),background-color .18s var(--ease),border-color .18s var(--ease);
}
.tag:hover{border-color:var(--neon);color:var(--neon)}
.tag.is-active,
.tag[aria-pressed="true"]{
  background:var(--neon);
  border-color:var(--neon);
  color:var(--abyss);
  font-weight:800;
}

/* ---------- 15. 折叠面板 ---------- */
.accordion{border-top:1px solid var(--lane)}
.accordion__item{border-bottom:1px solid var(--lane)}
.accordion__trigger{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  width:100%;
  padding:18px 0;
  text-align:left;
  font-size:16px;
  font-weight:800;
  color:inherit;
  transition:color .18s var(--ease);
}
.accordion__trigger:hover{color:var(--neon)}
.accordion__icon{
  flex:0 0 auto;
  font-family:var(--font-mono);
  font-size:15px;
  color:var(--neon);
  transition:transform .2s var(--ease);
}
.accordion__trigger[aria-expanded="true"] .accordion__icon{transform:rotate(45deg)}
.accordion__panel{
  padding:0 0 20px;
  font-size:15px;
  line-height:1.8;
  color:rgba(245,241,232,.8);
}
.section--paper .accordion__panel{color:#3A2B22}
.accordion__panel[hidden]{display:none}

/* ---------- 16. 面板 ---------- */
.panel{
  padding:clamp(18px,2.4vw,32px);
  background:var(--deep-teal);
  border:1px solid var(--lane);
  border-radius:2px;
}
.panel--cut{
  clip-path:polygon(0 0,calc(100% - 18px) 0,100% 18px,100% 100%,0 100%);
  border-radius:0;
}
.panel--paper{background:var(--sand);border-color:rgba(34,24,18,.14);color:var(--ink)}

/* ---------- 17. 图片容器 ---------- */
.media-frame{
  position:relative;
  overflow:hidden;
  border-radius:2px;
  background:linear-gradient(140deg,var(--mid-teal),var(--abyss));
  aspect-ratio:16 / 9;
  isolation:isolate;
}
.media-frame > img,
.media-frame > picture > img{
  width:100%;
  height:100%;
  object-fit:cover;
}
.media-frame::after{
  content:"";
  position:absolute;
  inset:0;
  z-index:1;
  pointer-events:none;
  background:
    radial-gradient(120% 90% at 18% 0%,rgba(53,230,208,.20),transparent 62%),
    repeating-linear-gradient(180deg,rgba(4,34,43,0) 0 3px,rgba(4,34,43,.14) 3px 4px);
}
.media-frame--tall{aspect-ratio:4 / 5}
.media-frame--square{aspect-ratio:1 / 1}
.media-frame--wide{aspect-ratio:21 / 9}
.media-frame__caption{
  position:absolute;
  left:0;
  right:0;
  bottom:0;
  z-index:2;
  padding:16px;
  font-size:12.5px;
  line-height:1.6;
  color:var(--frost);
  background:linear-gradient(0deg,rgba(4,34,43,.86),rgba(4,34,43,.35) 60%,transparent);
}

/* ---------- 18. 目录跟随 ---------- */
.toc{
  position:sticky;
  top:calc(var(--header-h) + 24px);
  padding-right:12px;
  border-right:1px solid var(--lane);
}
.toc__title{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.24em;
  text-transform:uppercase;
  color:var(--aqua);
  margin-bottom:14px;
}
.toc__list{display:flex;flex-direction:column}
.toc__link{
  display:flex;
  align-items:baseline;
  gap:10px;
  padding:9px 0 9px 14px;
  margin-left:-1px;
  border-left:2px solid rgba(53,230,208,.16);
  font-size:14px;
  line-height:1.5;
  color:rgba(245,241,232,.68);
  transition:color .18s var(--ease),border-color .18s var(--ease),background-color .18s var(--ease);
}
.toc__link:hover{color:var(--frost);border-left-color:var(--neon);background:rgba(53,230,208,.05)}
.toc__link[aria-current="true"]{
  color:var(--neon);
  border-left-color:var(--neon);
  font-weight:700;
}

/* ---------- 19. 返回顶部 ---------- */
.to-top{
  position:fixed;
  right:clamp(14px,3vw,30px);
  bottom:clamp(14px,3vw,30px);
  z-index:70;
  width:48px;
  height:48px;
  display:grid;
  place-items:center;
  background:rgba(8,59,71,.94);
  border:1px solid var(--mid-teal);
  color:var(--neon);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.06em;
  clip-path:polygon(0 0,100% 0,100% calc(100% - 12px),calc(100% - 12px) 100%,0 100%);
  opacity:0;
  pointer-events:none;
  transform:translateY(10px);
  transition:opacity .2s var(--ease),transform .2s var(--ease),border-color .18s var(--ease);
}
.to-top[data-visible]{
  opacity:1;
  pointer-events:auto;
  transform:none;
}
.to-top:hover{border-color:var(--neon)}

/* ---------- 20. 显现 ---------- */
[data-reveal]{
  opacity:0;
  transform:translateY(12px);
  transition:opacity .5s var(--ease),transform .5s var(--ease);
}
[data-reveal][data-revealed]{
  opacity:1;
  transform:none;
}

/* ---------- 21. footer ---------- */
.site-footer{
  position:relative;
  background:var(--abyss);
  color:var(--frost);
  margin-top:clamp(40px,7vw,110px);
  border-top:1px solid var(--lane);
}
.footer-slope{
  position:relative;
  height:clamp(52px,7vw,108px);
  background:
    repeating-linear-gradient(98deg,rgba(53,230,208,.20) 0 1px,transparent 1px 17px),
    linear-gradient(102deg,rgba(15,90,102,.9),rgba(8,59,71,.28) 58%,rgba(4,34,43,0) 92%);
  clip-path:polygon(0 100%,100% 0,100% 100%,0 100%);
}
.footer-slope::after{
  content:"";
  position:absolute;
  left:0;
  right:0;
  bottom:0;
  height:1px;
  background:linear-gradient(90deg,transparent,var(--neon) 40%,var(--orange) 70%,transparent);
  opacity:.6;
}

.footer-inner{
  max-width:var(--shell);
  margin-inline:auto;
  padding:0 var(--gutter) clamp(26px,4vw,44px);
}

.footer-grid{
  display:grid;
  grid-template-columns:1.5fr .85fr 1.15fr .8fr;
  gap:clamp(24px,4vw,56px);
  padding-top:clamp(18px,3vw,34px);
}

.footer-col{min-width:0}

.footer-brand .brand-link{padding-top:0}
.footer-tagline{
  margin-top:16px;
  font-size:15px;
  font-weight:800;
  letter-spacing:.01em;
  color:var(--frost);
}
.footer-note{
  margin-top:8px;
  font-size:12.5px;
  line-height:1.75;
  color:rgba(155,221,230,.82);
  max-width:34em;
}

.footer-title{
  margin-bottom:14px;
  font-family:var(--font-mono);
  font-size:11px;
  font-weight:400;
  letter-spacing:.24em;
  text-transform:uppercase;
  color:var(--aqua);
}

.footer-links a{
  display:inline-block;
  padding:5px 0;
  font-size:14.5px;
  color:rgba(245,241,232,.78);
  border-bottom:1px solid transparent;
  transition:color .18s var(--ease),border-color .18s var(--ease);
}
.footer-links a:hover{color:var(--neon);border-bottom-color:var(--neon)}

.footer-contact li{
  display:flex;
  flex-wrap:wrap;
  gap:4px 10px;
  padding:5px 0;
  font-size:14.5px;
  line-height:1.6;
  color:rgba(245,241,232,.82);
  overflow-wrap:anywhere;
}
.footer-k{
  flex:0 0 auto;
  min-width:44px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  color:var(--slate);
  padding-top:3px;
}

.footer-base{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:10px 28px;
  margin-top:clamp(26px,4vw,52px);
  padding-top:18px;
  border-top:1px solid var(--lane);
  font-size:12.5px;
  color:var(--slate);
}
.footer-copy{letter-spacing:.04em}
.footer-icp{
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  color:var(--aqua);
}

/* ---------- 22. 响应式 ---------- */
@media (max-width:1023px){
  :root{--header-h:66px}

  .lane-gap{display:none}

  .nav-toggle{display:inline-flex;margin-left:auto}

  .nav-scrim{display:block}

  .site-nav{
    position:fixed;
    top:0;
    right:0;
    bottom:0;
    z-index:2;
    width:min(372px,88vw);
    padding:calc(var(--header-h) + 22px) 26px 40px;
    background:linear-gradient(162deg,#083B47,#04222B 62%);
    border-left:1px solid var(--lane-strong);
    box-shadow:-18px 0 42px rgba(0,0,0,.42);
    overflow-y:auto;
    align-items:stretch;
    transform:translateX(102%);
    transition:transform .3s var(--ease);
  }
  .nav-list{
    flex-direction:column;
    align-items:stretch;
    gap:0;
  }
  .nav-link{
    flex-wrap:wrap;
    gap:4px 10px;
    padding:15px 0;
    font-size:16.5px;
    border-bottom:1px solid var(--lane);
  }
  .nav-link::after{display:none}
  .nav-num{font-size:11px;padding-top:4px}
  .nav-desc{
    display:block;
    flex:0 0 100%;
    font-size:12.5px;
    line-height:1.6;
    color:rgba(155,221,230,.78);
  }
  .nav-link[aria-current="page"]{
    color:var(--neon);
    border-bottom-color:var(--lane-strong);
  }
  .nav-link[aria-current="page"] .nav-desc{color:rgba(245,241,232,.86)}
  .nav-meta{display:block}

  .site-header[data-open] .site-nav{transform:none}
  .site-header[data-open] .nav-scrim{opacity:1;pointer-events:auto}

  .grid12 > [class*="col-"]{grid-column:1 / -1}
  .col-3[data-keep]{grid-column:span 6}
}

@media (max-width:900px){
  .footer-grid{grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:1 / -1}
  .toc{
    position:static;
    border-right:0;
    border-bottom:1px solid var(--lane);
    padding-right:0;
    padding-bottom:14px;
  }
  .toc__list{flex-direction:row;flex-wrap:wrap;gap:6px}
  .toc__link{
    border-left:0;
    border-bottom:2px solid rgba(53,230,208,.16);
    padding:7px 10px;
    margin-left:0;
  }
  .toc__link[aria-current="true"]{border-bottom-color:var(--neon)}
}

@media (max-width:640px){
  :root{--header-h:62px}

  body{font-size:16px}

  .brand-mark{width:28px;height:28px}
  .brand-cn{font-size:16px}
  .brand-en{font-size:9px;letter-spacing:.14em}

  .nav-toggle{padding:9px 11px;font-size:12px}
  .nav-toggle-text{display:none}

  .display{transform:none}
  .index-row{
    grid-template-columns:auto minmax(0,1fr) auto;
    padding:15px 4px;
  }
  .index-arrow{display:none}
  .member-ladder{height:150px}
  .footer-grid{grid-template-columns:1fr}
  .footer-base{justify-content:flex-start}
}

/* ---------- 23. 动效与无障碍 ---------- */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  [data-reveal]{opacity:1;transform:none}
  .lane-gap span{transform:none}
  .to-top{transform:none}
}