/* =============================================================
   百人牛牛网络 · 中国站  —  共享样式  /assets/site.css
   骨架：纵向叙事长卷 · 框架式导航 · 夜间牌桌底色
   ============================================================= */

:root{
  --ink-bg:#0B1F1A;
  --ink-card:#102A23;
  --ink-lift:#16382E;
  --line:#1F4A3D;
  --cyan:#38E1C8;
  --cyan-dim:#1E9C8B;
  --gold:#E9B949;
  --gold-soft:#F5D98A;
  --violet:#8B5CF6;
  --text:#E9F2EE;
  --muted:#9FB8AE;
  --deep:#05100D;

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

  --shell:1240px;
  --pad:24px;
  --header-h:76px;
  --edge:2px;
}

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

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

body{
  margin:0;
  color:var(--text);
  font-family:var(--font-sans);
  font-size:16px;
  font-weight:400;
  line-height:1.85;
  letter-spacing:.004em;
  background-color:var(--ink-bg);
  background-image:
    radial-gradient(1200px 720px at 84% -14%, rgba(56,225,200,.11), transparent 62%),
    radial-gradient(920px 640px at -12% 40%, rgba(139,92,246,.075), transparent 60%),
    linear-gradient(180deg,#0B1F1A 0%,#0A1C17 58%,#05100D 100%);
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

main{display:block;}
#main-content{scroll-margin-top:calc(var(--header-h) + 16px);}

h1,h2,h3,h4{
  margin:0;
  font-weight:900;
  line-height:1.28;
  letter-spacing:-.02em;
  color:var(--text);
}
p{margin:0 0 1.2em;}
p:last-child{margin-bottom:0;}
a{color:var(--cyan);text-decoration:none;}
a:hover{color:var(--gold-soft);}
img,svg,picture{max-width:100%;}
ul,ol{margin:0;padding:0;list-style:none;}
button{font:inherit;color:inherit;}
hr{border:0;border-top:1px solid var(--line);margin:0;}

:focus-visible{
  outline:2px solid var(--cyan);
  outline-offset:3px;
  border-radius:1px;
}

/* ---------- 跳至主要内容 ---------- */
.skip-link{
  position:absolute;
  left:14px;
  top:-72px;
  z-index:120;
  padding:10px 18px;
  background:var(--cyan);
  color:#04140F;
  font-weight:800;
  font-size:14px;
  letter-spacing:.02em;
  text-decoration:none;
  border:1px solid var(--cyan);
  transition:top .2s ease;
}
.skip-link:focus{top:12px;color:#04140F;}

/* =============================================================
   框架式头部
   ============================================================= */
.site-header{
  position:sticky;
  top:0;
  z-index:80;
  background:rgba(11,31,26,.94);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
  border-bottom:1px solid var(--line);
}
.site-header::after{
  content:"";
  position:absolute;
  left:0;
  right:0;
  bottom:-1px;
  height:1px;
  background:linear-gradient(90deg,var(--cyan) 0%,var(--cyan-dim) 28%,transparent 62%);
  opacity:.55;
  pointer-events:none;
}

.header-inner{
  position:relative;
  max-width:var(--shell);
  margin:0 auto;
  padding:0 var(--pad);
  min-height:var(--header-h);
  display:grid;
  grid-template-columns:auto minmax(0,1fr) auto;
  align-items:center;
  gap:26px;
}

.brand-block{min-width:0;}
.brand-mark{
  display:flex;
  align-items:center;
  gap:12px;
  text-decoration:none;
  color:inherit;
}
.brand-mark:hover{color:inherit;}
.brand-glyph{
  flex:none;
  width:42px;
  height:42px;
  display:grid;
  place-items:center;
  font-size:20px;
  font-weight:900;
  line-height:1;
  color:#04140F;
  background:linear-gradient(140deg,var(--cyan) 0%,var(--cyan-dim) 100%);
  clip-path:polygon(14% 0,100% 0,86% 100%,0 100%);
  box-shadow:0 0 22px -8px rgba(56,225,200,.7);
}
.brand-text{display:flex;flex-direction:column;min-width:0;}
.brand-line{
  font-size:15px;
  font-weight:800;
  letter-spacing:.01em;
  color:var(--text);
  white-space:nowrap;
}
.brand-tagline{
  font-family:var(--font-mono);
  font-size:11px;
  line-height:1.5;
  letter-spacing:.06em;
  color:var(--muted);
  white-space:nowrap;
}

/* 导航刻度 */
.frame-nav{min-width:0;}
.frame-nav-list{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:center;
  gap:2px;
}
.frame-link{
  position:relative;
  display:block;
  padding:8px 11px;
  font-size:13px;
  font-weight:500;
  letter-spacing:.02em;
  color:var(--muted);
  text-decoration:none;
  border:1px solid transparent;
  transition:color .18s ease,border-color .18s ease,background-color .18s ease;
}
.frame-link:hover,
.frame-link:focus-visible{
  color:var(--text);
  border-color:var(--line);
  background:rgba(56,225,200,.05);
}
.frame-link[aria-current="page"]{
  color:var(--cyan);
  border-color:var(--cyan-dim);
  background:rgba(56,225,200,.09);
}
.frame-link[aria-current="page"]::before{
  content:"";
  position:absolute;
  left:11px;
  right:11px;
  bottom:3px;
  height:1px;
  background:var(--cyan);
  opacity:.7;
}

.header-actions{
  display:flex;
  align-items:center;
  gap:10px;
}

/* 按钮 */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:10px 18px;
  font-size:14px;
  font-weight:700;
  letter-spacing:.02em;
  text-decoration:none;
  white-space:nowrap;
  border:1px solid var(--line);
  background:transparent;
  color:var(--text);
  cursor:pointer;
  transition:background-color .18s ease,color .18s ease,border-color .18s ease,transform .18s ease;
}
.btn:hover{transform:translateY(-1px);}
.btn-solid{
  background:var(--cyan);
  border-color:var(--cyan);
  color:#04140F;
}
.btn-solid:hover{background:var(--cyan-dim);border-color:var(--cyan-dim);color:#04140F;}
.btn-ghost{
  color:var(--cyan);
  border-color:var(--cyan-dim);
}
.btn-ghost:hover{background:rgba(56,225,200,.1);border-color:var(--cyan);color:var(--cyan);}

/* 移动导航按钮 */
.nav-toggle{
  display:none;
  align-items:center;
  gap:9px;
  padding:9px 12px;
  background:transparent;
  border:1px solid var(--line);
  color:var(--text);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  cursor:pointer;
  transition:color .18s ease,border-color .18s ease,background-color .18s ease;
}
.nav-toggle:hover{border-color:var(--cyan);color:var(--cyan);}
.nav-toggle[aria-expanded="true"]{border-color:var(--cyan);color:var(--cyan);background:rgba(56,225,200,.08);}
.nav-toggle-icon{
  display:inline-flex;
  flex-direction:column;
  justify-content:center;
  gap:4px;
  width:16px;
  height:14px;
}
.nav-toggle-icon span{
  display:block;
  width:100%;
  height:1.5px;
  background:currentColor;
  transition:transform .24s ease,opacity .24s ease;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(1){transform:translateY(5.5px) rotate(45deg);}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(2){opacity:0;}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(3){transform:translateY(-5.5px) rotate(-45deg);}
.nav-toggle-label{font-weight:500;}

/* =============================================================
   页脚：深黑底抽屉
   ============================================================= */
.site-footer{
  position:relative;
  margin-top:96px;
  background:var(--deep);
  border-top:1px solid var(--line);
  color:var(--muted);
  font-size:14px;
}
.site-footer::before{
  content:"";
  position:absolute;
  top:0;
  left:0;
  right:0;
  height:2px;
  background:linear-gradient(90deg,var(--cyan) 0%,var(--cyan-dim) 26%,transparent 68%);
  opacity:.6;
}

.footer-inner{
  max-width:var(--shell);
  margin:0 auto;
  padding:58px var(--pad) 34px;
  display:grid;
  grid-template-columns:minmax(240px,1.35fr) minmax(0,2fr);
  gap:44px;
}

.footer-brand-line{
  margin:0 0 12px;
  max-width:24em;
  font-size:15px;
  font-weight:800;
  line-height:1.6;
  letter-spacing:.01em;
  color:var(--text);
}
.footer-note{
  margin:0;
  max-width:30em;
  font-size:13px;
  line-height:1.8;
  color:var(--muted);
}

.footer-columns{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:26px;
}
.footer-col-title{
  margin:0 0 14px;
  font-family:var(--font-mono);
  font-size:12px;
  font-weight:700;
  letter-spacing:.24em;
  color:var(--cyan-dim);
}
.footer-list li{margin-bottom:10px;}
.footer-list a{
  font-size:14px;
  color:var(--muted);
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:color .18s ease,border-color .18s ease;
}
.footer-list a:hover,
.footer-list a:focus-visible{color:var(--cyan);border-bottom-color:var(--cyan-dim);}

.footer-contact{
  border-top:1px solid var(--line);
  background:linear-gradient(180deg,rgba(16,42,35,.7),transparent);
}
.footer-contact-inner{
  max-width:var(--shell);
  margin:0 auto;
  padding:24px var(--pad);
  display:flex;
  flex-wrap:wrap;
  gap:14px 36px;
}
.contact-item{
  margin:0;
  display:flex;
  flex-wrap:wrap;
  align-items:baseline;
  gap:9px;
}
.contact-key{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  color:var(--cyan-dim);
}
.contact-val{
  font-size:14px;
  color:var(--text);
  word-break:break-word;
}

.footer-meta{
  max-width:var(--shell);
  margin:0 auto;
  padding:18px var(--pad) 34px;
  border-top:1px solid rgba(31,74,61,.65);
  display:flex;
  flex-wrap:wrap;
  justify-content:space-between;
  align-items:center;
  gap:10px 24px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.03em;
  color:var(--muted);
}
.footer-meta p{margin:0;}
.copyright{color:var(--muted);}
.copyright [data-year]{color:var(--gold);font-weight:700;}

/* =============================================================
   基础版式组件（页面阶段复用）
   ============================================================= */
.page-shell{
  width:100%;
  max-width:var(--shell);
  margin:0 auto;
  padding:0 var(--pad);
}

.breadcrumbs{
  max-width:var(--shell);
  margin:26px auto 0;
  padding:0 var(--pad);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.06em;
  color:var(--muted);
}
.breadcrumbs ol{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
}
.breadcrumbs li{display:flex;align-items:center;gap:8px;}
.breadcrumbs li + li::before{
  content:"/";
  color:var(--line);
}
.breadcrumbs a{color:var(--muted);border-bottom:1px solid transparent;}
.breadcrumbs a:hover{color:var(--cyan);border-bottom-color:var(--cyan-dim);}
.breadcrumbs [aria-current="page"]{color:var(--text);}

.lede{
  max-width:56ch;
  font-size:17px;
  line-height:1.9;
  color:var(--muted);
}

/* 章节三件套 */
.section-head{
  display:grid;
  grid-template-columns:auto minmax(0,1fr) auto;
  gap:22px;
  align-items:start;
  margin:0 0 30px;
  padding-top:8px;
}
.section-index{
  font-family:var(--font-mono);
  font-size:clamp(52px,7vw,104px);
  font-weight:700;
  line-height:.8;
  letter-spacing:-.05em;
  color:var(--cyan);
  opacity:.92;
}
.section-title{
  align-self:center;
  font-size:clamp(23px,2.6vw,32px);
  font-weight:900;
  letter-spacing:-.02em;
}
.section-note{
  writing-mode:vertical-rl;
  font-family:var(--font-mono);
  font-size:12px;
  line-height:1;
  letter-spacing:.26em;
  color:var(--muted);
  padding-top:4px;
}

/* 牌面卡片 */
.board-card{
  position:relative;
  background:var(--ink-card);
  border:1px solid var(--line);
  padding:22px;
  transition:transform .24s ease,border-color .24s ease,box-shadow .24s ease,background-color .24s ease;
}
.board-card:hover,
.board-card:focus-within{
  transform:translateY(-4px);
  border-color:var(--cyan);
  background:var(--ink-lift);
  box-shadow:0 20px 44px -26px rgba(56,225,200,.45);
}

.tag{
  display:inline-block;
  padding:3px 9px;
  font-family:var(--font-mono);
  font-size:11px;
  line-height:1.6;
  letter-spacing:.08em;
  color:var(--gold);
  background:rgba(233,185,73,.09);
  border:1px solid rgba(233,185,73,.42);
}

/* 图片容器（页面阶段放置图片） */
.media-frame{
  position:relative;
  display:block;
  width:100%;
  overflow:hidden;
  background:linear-gradient(152deg,var(--ink-card) 0%,var(--deep) 100%);
  border:1px solid var(--line);
}
.media-frame img{
  display:block;
  width:100%;
  height:100%;
  object-fit:cover;
}
.media-frame::after{
  content:"";
  position:absolute;
  inset:0;
  pointer-events:none;
  background:linear-gradient(202deg,rgba(56,225,200,.16) 0%,rgba(56,225,200,0) 46%,rgba(5,16,13,.5) 100%);
}
.media-tall{aspect-ratio:3 / 4;}
.media-wide{aspect-ratio:16 / 9;}
.media-square{aspect-ratio:1 / 1;}

/* 翻面专题卡 */
.flip-card{
  position:relative;
  height:250px;
  perspective:1200px;
}
.flip-card-inner{
  position:absolute;
  inset:0;
  transition:transform .42s ease;
  transform-style:preserve-3d;
}
.flip-card:hover .flip-card-inner,
.flip-card:focus-within .flip-card-inner,
.flip-card[data-flipped] .flip-card-inner{transform:rotateY(180deg);}
.flip-face{
  position:absolute;
  inset:0;
  padding:22px;
  background:var(--ink-card);
  border:1px solid var(--line);
  backface-visibility:hidden;
  -webkit-backface-visibility:hidden;
  overflow:auto;
  display:flex;
  flex-direction:column;
  gap:10px;
}
.flip-face:hover{border-color:var(--cyan);}
.flip-back{
  transform:rotateY(180deg);
  background:var(--ink-lift);
  border-color:var(--cyan-dim);
}

/* 页面内主题筛选 */
.filter-bar{
  display:flex;
  flex-wrap:wrap;
  gap:8px;
  margin:0 0 24px;
}
.filter-btn{
  padding:7px 14px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  color:var(--muted);
  background:transparent;
  border:1px solid var(--line);
  cursor:pointer;
  transition:color .18s ease,border-color .18s ease,background-color .18s ease;
}
.filter-btn:hover{color:var(--cyan);border-color:var(--cyan-dim);}
.filter-btn.is-active{
  color:#F6F0FF;
  border-color:var(--violet);
  background:rgba(139,92,246,.2);
}

/* 滚动进度与返回顶部（由 JS 注入） */
.scroll-progress{
  position:fixed;
  top:0;
  right:0;
  width:3px;
  height:100vh;
  z-index:90;
  pointer-events:none;
  background:rgba(31,74,61,.35);
}
.scroll-progress-bar{
  width:100%;
  height:0;
  background:linear-gradient(180deg,var(--cyan) 0%,var(--cyan-dim) 100%);
  box-shadow:0 0 14px rgba(56,225,200,.55);
}
.to-top{
  position:fixed;
  right:20px;
  bottom:24px;
  z-index:88;
  width:44px;
  height:44px;
  display:grid;
  place-items:center;
  font-family:var(--font-mono);
  font-size:16px;
  color:var(--cyan);
  background:var(--ink-card);
  border:1px solid var(--line);
  cursor:pointer;
  opacity:0;
  visibility:hidden;
  transform:translateY(10px);
  transition:opacity .24s ease,transform .24s ease,visibility .24s ease,border-color .18s ease;
}
.to-top[data-visible]{opacity:1;visibility:visible;transform:none;}
.to-top:hover{border-color:var(--cyan);background:var(--ink-lift);}

/* 章节入场 */
.js-reveal [data-reveal]{
  opacity:0;
  transform:translateY(14px);
  transition:opacity .5s ease,transform .5s ease;
}
.js-reveal [data-reveal][data-revealed]{
  opacity:1;
  transform:none;
}

@keyframes cardIn{
  from{opacity:0;transform:translateY(10px) scale(.992);}
  to{opacity:1;transform:none;}
}

/* =============================================================
   响应式
   ============================================================= */
@media (max-width:1180px){
  .header-inner{gap:16px;}
  .frame-link{padding:8px 9px;font-size:12.5px;}
  .brand-tagline{display:none;}
}

@media (max-width:1080px){
  :root{--pad:18px;--header-h:66px;}

  .header-inner{
    grid-template-columns:minmax(0,1fr) auto;
    min-height:var(--header-h);
  }
  .header-actions{display:none;}
  .nav-toggle{display:inline-flex;}
  .brand-tagline{display:block;}

  .frame-nav{
    position:absolute;
    left:0;
    right:0;
    top:100%;
    background:var(--ink-card);
    border-top:1px solid var(--line);
    border-bottom:1px solid var(--line);
    max-height:0;
    overflow:hidden;
    transition:max-height .32s ease;
  }
  .frame-nav[data-open]{
    max-height:min(72vh,540px);
    overflow-y:auto;
  }
  .frame-nav-list{
    flex-direction:column;
    align-items:stretch;
    justify-content:flex-start;
    gap:0;
    padding:10px 18px 18px;
  }
  .frame-nav-list li{width:100%;}
  .frame-link{
    padding:13px 12px;
    font-size:15px;
    border-bottom:1px solid rgba(31,74,61,.6);
  }
  .frame-link[aria-current="page"]{background:rgba(56,225,200,.09);}
  .frame-link[aria-current="page"]::before{display:none;}

  .section-head{
    grid-template-columns:auto minmax(0,1fr);
    gap:16px;
  }
  .section-note{
    grid-column:2;
    writing-mode:horizontal-tb;
    letter-spacing:.18em;
  }
}

@media (max-width:900px){
  .footer-inner{
    grid-template-columns:minmax(0,1fr);
    gap:34px;
    padding:44px var(--pad) 30px;
  }
  .footer-brand-line{max-width:none;}
}

@media (max-width:680px){
  body{font-size:15.5px;}
  .footer-columns{grid-template-columns:repeat(2,minmax(0,1fr));}
  .footer-contact-inner{flex-direction:column;gap:12px;}
  .footer-meta{flex-direction:column;align-items:flex-start;gap:6px;}
  .to-top{right:14px;bottom:16px;}
}

@media (max-width:460px){
  .footer-columns{grid-template-columns:minmax(0,1fr);gap:22px;}
  .filter-btn{padding:6px 11px;font-size:11.5px;}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto;}
  *,
  *::before,
  *::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  .js-reveal [data-reveal]{opacity:1 !important;transform:none !important;}
  .board-card:hover,
  .board-card:focus-within{transform:none;}
  .btn:hover{transform:none;}
}