/* ==========================================================================
   必嬴CN · 共享站点外壳样式
   路径：/assets/site.css
   仅承载 reset、变量、页头、页脚、通用组件与基础网格
   ========================================================================== */

/* ---------- 1. 设计变量 ---------- */
:root{
  --by-red:#E23A2E;
  --by-red-deep:#C21F2C;
  --by-orange:#F0532F;
  --by-navy:#12233F;
  --by-night:#0C1A2E;
  --by-cream:#F7F1E6;
  --by-sand:#E4B25C;
  --by-ink:#241A16;
  --by-mist:#DCE4EF;
  --by-slate:#5A6B85;
  --by-paper:#FFFDF8;
  --by-green:#2F8F6B;

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

  --r-sm:10px;
  --r-md:16px;
  --r-lg:24px;
  --r-xl:32px;
  --r-pill:999px;

  --hdr-h:78px;
  --hdr-h-stuck:64px;
  --shell-max:1280px;
  --shell-pad:20px;

  --ease:cubic-bezier(.22,.61,.36,1);
  --shadow-soft:0 22px 48px -34px rgba(18,35,63,.55);
}

@media (max-width:960px){
  :root{
    --hdr-h:62px;
    --hdr-h-stuck:62px;
  }
}

/* ---------- 2. Reset ---------- */
*,*::before,*::after{box-sizing:border-box;}

html{
  -webkit-text-size-adjust:100%;
  text-size-adjust:100%;
  scroll-behavior:smooth;
}

body{
  margin:0;
  min-height:100vh;
  display:flex;
  flex-direction:column;
  background-color:var(--by-cream);
  color:var(--by-ink);
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.75;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
}

img,svg,video,canvas{display:block;max-width:100%;height:auto;}
button,input,select,textarea{font:inherit;color:inherit;}
button{padding:0;border:0;background:none;cursor:pointer;}
a{color:inherit;text-decoration:none;}
ul,ol{margin:0;padding:0;list-style:none;}
h1,h2,h3,h4,h5,h6,p,figure,blockquote,dl,dd{margin:0;}
h1,h2,h3,h4,h5,h6{line-height:1.15;font-weight:800;letter-spacing:-.01em;}
table{border-collapse:collapse;width:100%;}
hr{border:0;margin:0;}
strong,b{font-weight:700;}

/* ---------- 3. 焦点与无障碍 ---------- */
:focus-visible{
  outline:3px solid var(--by-red);
  outline-offset:3px;
  border-radius:6px;
}
.site-header[data-stuck="true"] :focus-visible{outline-color:var(--by-sand);}
.site-footer :focus-visible{outline-color:var(--by-sand);}

.visually-hidden{
  position:absolute;
  width:1px;height:1px;
  margin:-1px;padding:0;border:0;
  overflow:hidden;clip:rect(0 0 0 0);clip-path:inset(50%);
  white-space:nowrap;
}

/* ---------- 4. 布局容器 ---------- */
.shell{
  width:min(calc(100% - (var(--shell-pad) * 2)),var(--shell-max));
  margin-inline:auto;
}

.site-main{
  flex:1 0 auto;
  padding-top:var(--hdr-h);
}

.site-main--overlay{padding-top:0;}

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

@media (max-width:960px){
  .grid-12{
    grid-template-columns:repeat(4,minmax(0,1fr));
    gap:16px;
  }
}

/* ---------- 5. 页头 ---------- */
.skip-link{
  position:absolute;
  left:16px;
  top:0;
  z-index:200;
  padding:11px 20px;
  border-radius:0 0 14px 14px;
  background:var(--by-red);
  color:#fff;
  font-size:14px;
  font-weight:600;
  transform:translateY(-160%);
  transition:transform .2s var(--ease);
}
.skip-link:focus-visible{transform:translateY(0);}

.site-header{
  position:fixed;
  top:0;left:0;right:0;
  z-index:80;

  --hdr-bg:transparent;
  --hdr-fg:var(--by-navy);
  --hdr-muted:rgba(18,35,63,.6);
  --hdr-line:rgba(18,35,63,.18);

  background-color:var(--hdr-bg);
  color:var(--hdr-fg);
  border-bottom:1px solid transparent;
  transition:background-color .28s var(--ease),
             color .28s var(--ease),
             border-color .28s var(--ease);
}

.site-header[data-stuck="true"]{
  --hdr-bg:var(--by-navy);
  --hdr-fg:var(--by-cream);
  --hdr-muted:rgba(247,241,230,.66);
  --hdr-line:rgba(247,241,230,.22);
  border-bottom-color:rgba(247,241,230,.14);
}

.header-inner{
  display:flex;
  align-items:center;
  gap:20px;
  height:var(--hdr-h);
  transition:height .28s var(--ease);
}

.site-header[data-stuck="true"] .header-inner{height:var(--hdr-h-stuck);}

.brand{
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  gap:10px;
}

.brand-mark{
  position:relative;
  display:block;
  width:28px;
  height:28px;
  flex:0 0 auto;
  border:2px solid currentColor;
  border-radius:9px;
}
.brand-mark::before,
.brand-mark::after{
  content:"";
  position:absolute;
  background:var(--by-red);
  border-radius:2px;
}
.brand-mark::before{left:50%;top:5px;bottom:5px;width:2px;transform:translateX(-50%);}
.brand-mark::after{top:50%;left:5px;right:5px;height:2px;transform:translateY(-50%);}

.brand-words{
  display:flex;
  flex-direction:column;
  line-height:1.1;
}
.brand-cn{
  font-size:19px;
  font-weight:800;
  letter-spacing:.01em;
}
.brand-sub{
  font-family:var(--font-mono);
  font-size:9px;
  letter-spacing:.2em;
  color:var(--hdr-muted);
  margin-top:2px;
}

.site-nav{
  flex:1 1 auto;
  display:flex;
  justify-content:flex-end;
}

.nav-list{
  display:flex;
  align-items:center;
  gap:2px;
}

.nav-lead{display:none;}

.nav-link{
  position:relative;
  display:inline-block;
  padding:10px 13px;
  font-size:15px;
  letter-spacing:.02em;
  color:var(--hdr-fg);
  white-space:nowrap;
  transition:color .2s var(--ease);
}
.nav-link::after{
  content:"";
  position:absolute;
  left:13px;right:13px;bottom:3px;
  height:2px;
  border-radius:2px;
  background:var(--by-sand);
  transform:scaleX(0);
  transform-origin:0 50%;
  transition:transform .24s var(--ease);
}
.nav-link:hover::after,
.nav-link:focus-visible::after,
.nav-link[aria-current="page"]::after{transform:scaleX(1);}
.nav-link[aria-current="page"]{color:var(--hdr-fg);}

.header-tools{
  flex:0 0 auto;
  display:flex;
  align-items:center;
  gap:10px;
}

.btn-cta{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:11px 20px;
  border-radius:var(--r-pill);
  background:var(--by-red);
  color:#fff;
  font-size:14px;
  font-weight:600;
  letter-spacing:.03em;
  white-space:nowrap;
  transition:background-color .2s var(--ease),transform .2s var(--ease);
}
.btn-cta::after{
  content:"";
  width:6px;height:6px;
  border-radius:2px;
  background:var(--by-sand);
  flex:0 0 auto;
}
.btn-cta:hover{background:var(--by-red-deep);}
.btn-cta:active{transform:translateY(1px);}

.nav-toggle{
  display:none;
  align-items:center;
  gap:9px;
  padding:9px 14px;
  border-radius:var(--r-pill);
  border:1.5px solid var(--hdr-line);
  color:var(--hdr-fg);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.1em;
  transition:border-color .2s var(--ease);
}
.nav-toggle-bars{
  position:relative;
  display:block;
  width:16px;
  height:10px;
}
.nav-toggle-bars::before,
.nav-toggle-bars::after{
  content:"";
  position:absolute;
  left:0;right:0;
  height:2px;
  border-radius:2px;
  background:currentColor;
  transition:transform .24s var(--ease);
}
.nav-toggle-bars::before{top:0;}
.nav-toggle-bars::after{bottom:0;}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before{transform:translateY(4px) rotate(45deg);}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after{transform:translateY(-4px) rotate(-45deg);}
.nav-toggle-label{line-height:1;}

.scroll-progress{
  position:absolute;
  left:0;right:0;bottom:-1px;
  height:2px;
  background:transparent;
  pointer-events:none;
}
.scroll-progress-bar{
  display:block;
  height:2px;
  width:100%;
  transform:scaleX(0);
  transform-origin:0 50%;
  background:linear-gradient(90deg,var(--by-sand) 0%,var(--by-sand) 72%,var(--by-red) 100%);
}

/* ---------- 6. 移动端导航 ---------- */
@media (max-width:960px){
  .nav-toggle{display:inline-flex;}

  .site-nav{
    position:fixed;
    inset:0;
    z-index:60;
    display:none;
    flex-direction:column;
    justify-content:flex-start;
    padding:calc(var(--hdr-h) + 20px) var(--shell-pad) 48px;
    background-color:var(--by-navy);
    color:var(--by-cream);
    overflow-y:auto;
    -webkit-overflow-scrolling:touch;
    border-bottom:0;
  }
  .site-nav[data-open="true"]{display:flex;}

  .nav-list{
    flex-direction:column;
    align-items:stretch;
    gap:0;
    width:100%;
    max-width:620px;
    margin-inline:auto;
  }

  .nav-lead{
    display:block;
    margin-bottom:18px;
    padding-bottom:18px;
    border-bottom:1px solid rgba(247,241,230,.16);
  }
  .nav-lead-link{
    display:inline-flex;
    align-items:center;
    gap:8px;
    padding:12px 22px;
    border-radius:var(--r-pill);
    background:var(--by-red);
    color:#fff;
    font-size:15px;
    font-weight:600;
    letter-spacing:.03em;
  }
  .nav-lead-link::after{
    content:"";
    width:6px;height:6px;
    border-radius:2px;
    background:var(--by-sand);
  }

  .nav-link{
    display:block;
    padding:15px 2px;
    font-size:19px;
    color:var(--by-cream);
    border-bottom:1px solid rgba(247,241,230,.1);
  }
  .nav-link::after{display:none;}
  .nav-link[aria-current="page"]{
    color:var(--by-sand);
    padding-left:16px;
  }
  .nav-link[aria-current="page"]::before{
    content:"";
    position:absolute;
    left:0;top:50%;
    width:8px;height:2px;
    background:var(--by-red);
    transform:translateY(-50%);
  }

  .header-tools{margin-left:auto;}
  .btn-cta{padding:9px 16px;font-size:13px;}
}

@media (max-width:520px){
  .brand-sub{display:none;}
  .nav-toggle-label{display:none;}
  .nav-toggle{padding:10px 12px;}
}

/* ---------- 7. 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:auto;
  color:var(--by-cream);
  background-color:var(--by-navy);
  background-image:
    radial-gradient(circle at 10% 0%,rgba(226,58,46,.20),transparent 44%),
    radial-gradient(circle at 92% 6%,rgba(228,178,92,.14),transparent 46%);
}
.site-footer::before{
  content:"";
  position:absolute;
  top:0;left:0;right:0;
  height:4px;
  background:linear-gradient(90deg,var(--by-orange) 0%,var(--by-red-deep) 52%,var(--by-navy) 100%);
}

.footer-grid{
  display:grid;
  grid-template-columns:1.5fr .9fr 1.1fr 1.2fr;
  gap:44px 32px;
  padding:68px 0 52px;
}

.footer-col{min-width:0;}

.footer-brand{
  display:inline-flex;
  align-items:center;
  gap:10px;
}
.footer-brand .brand-mark{width:26px;height:26px;}
.footer-brand .brand-cn{font-size:18px;font-weight:800;color:var(--by-cream);}
.footer-brand .brand-sub{color:rgba(247,241,230,.5);}

.footer-tagline{
  margin-top:18px;
  max-width:34ch;
  font-size:15px;
  line-height:1.8;
  color:rgba(247,241,230,.72);
}

.footer-icp{
  margin-top:18px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  color:rgba(247,241,230,.5);
}

.footer-heading{
  display:flex;
  align-items:center;
  gap:12px;
  font-family:var(--font-mono);
  font-size:12px;
  font-weight:500;
  letter-spacing:.14em;
  color:var(--by-sand);
  line-height:1.4;
}
.footer-heading::after{
  content:"";
  flex:1 1 auto;
  height:1px;
  background:rgba(228,178,92,.34);
}

.footer-links{margin-top:20px;}
.footer-links li+li{margin-top:11px;}
.footer-links a{
  display:inline-block;
  font-size:15px;
  line-height:1.6;
  color:rgba(247,241,230,.78);
  border-bottom:1px solid transparent;
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.footer-links a:hover,
.footer-links a:focus-visible{
  color:var(--by-sand);
  border-bottom-color:rgba(228,178,92,.55);
}

.footer-contact{margin-top:20px;}
.footer-contact li{
  display:flex;
  gap:10px;
  align-items:baseline;
  font-size:15px;
  line-height:1.7;
}
.footer-contact li+li{margin-top:10px;}
.footer-k{
  flex:0 0 auto;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  color:var(--by-sand);
}
.footer-v{
  color:rgba(247,241,230,.8);
  word-break:break-word;
}

.footer-note{
  margin-top:16px;
  max-width:44ch;
  font-size:13px;
  line-height:1.75;
  color:rgba(247,241,230,.55);
}

.footer-bottom{
  border-top:1px solid rgba(247,241,230,.14);
}
.footer-bottom-inner{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:12px 24px;
  padding:20px 0 26px;
  font-size:13px;
  color:rgba(247,241,230,.55);
}
.footer-copy{font-family:var(--font-mono);letter-spacing:.04em;}
.footer-legal{
  display:flex;
  flex-wrap:wrap;
  gap:8px 22px;
}
.footer-legal a{
  color:rgba(247,241,230,.62);
  border-bottom:1px solid rgba(247,241,230,.26);
  padding-bottom:1px;
  transition:color .2s var(--ease),border-color .2s var(--ease);
}
.footer-legal a:hover,
.footer-legal a:focus-visible{
  color:var(--by-sand);
  border-bottom-color:var(--by-sand);
}

@media (max-width:1024px){
  .footer-grid{
    grid-template-columns:1fr 1fr;
    gap:40px 28px;
    padding:56px 0 44px;
  }
  .footer-col--brand{grid-column:1 / -1;}
  .footer-tagline{max-width:52ch;}
}

@media (max-width:600px){
  .footer-grid{
    grid-template-columns:1fr;
    gap:36px;
    padding:48px 0 36px;
  }
  .footer-bottom-inner{
    flex-direction:column;
    align-items:flex-start;
    gap:14px;
  }
}

/* ---------- 8. 通用组件 ---------- */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:13px 26px;
  border-radius:var(--r-pill);
  font-size:15px;
  font-weight:600;
  letter-spacing:.03em;
  line-height:1.2;
  transition:background-color .2s var(--ease),
             color .2s var(--ease),
             border-color .2s var(--ease),
             transform .2s var(--ease);
}
.btn:active{transform:translateY(1px);}

.btn-primary{
  background:var(--by-red);
  color:#fff;
}
.btn-primary:hover{background:var(--by-red-deep);}

.btn-ghost{
  border:1.5px solid rgba(36,26,22,.24);
  color:var(--by-ink);
}
.btn-ghost:hover{
  border-color:var(--by-red);
  color:var(--by-red);
}

.pill{
  display:inline-flex;
  align-items:center;
  gap:7px;
  padding:6px 14px;
  border-radius:var(--r-pill);
  border:1px solid rgba(36,26,22,.16);
  background:var(--by-paper);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  line-height:1.6;
  color:var(--by-ink);
}

.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:3px 11px;
  border-radius:var(--r-pill);
  border:1px solid rgba(36,26,22,.18);
  font-size:12px;
  letter-spacing:.04em;
  line-height:1.7;
  color:var(--by-slate);
}
.tag--live{
  color:var(--by-green);
  border-color:rgba(47,143,107,.42);
  background:rgba(47,143,107,.08);
}
.tag--live::before{
  content:"";
  width:6px;height:6px;
  border-radius:50%;
  background:var(--by-green);
}

.num{
  font-family:var(--font-mono);
  letter-spacing:.08em;
  font-variant-numeric:tabular-nums;
}

.metric{
  font-family:var(--font-mono);
  font-weight:700;
  letter-spacing:.02em;
  font-variant-numeric:tabular-nums;
  padding:0 .34em;
  border-radius:6px;
  background:rgba(228,178,92,.3);
}

.section-marker{
  display:flex;
  align-items:center;
  gap:12px;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  line-height:1.6;
  color:var(--by-slate);
}
.section-marker::before{
  content:"";
  width:34px;
  height:2px;
  flex:0 0 auto;
  border-radius:2px;
  background:var(--by-sand);
}
.section-marker .num{transition:color .26s var(--ease);}
.section-marker.is-active{color:var(--by-ink);}
.section-marker.is-active .num{color:var(--by-red);}

.breadcrumb{
  font-family:var(--font-mono);
  font-size:13px;
  letter-spacing:.06em;
  color:var(--by-slate);
}
.breadcrumb ol{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
}
.breadcrumb li{display:inline-flex;align-items:center;}
.breadcrumb li+li::before{
  content:"/";
  margin-right:8px;
  color:var(--by-sand);
}
.breadcrumb a:hover,
.breadcrumb a:focus-visible{color:var(--by-red);}

.card{
  background:var(--by-paper);
  border:1px solid rgba(36,26,22,.1);
  border-radius:var(--r-lg);
  padding:24px;
}

.rule-sand{
  height:2px;
  border-radius:2px;
  background:linear-gradient(90deg,var(--by-sand) 0%,rgba(228,178,92,0) 100%);
}

.coord-field{
  position:relative;
  background-color:var(--by-cream);
  background-image:
    linear-gradient(rgba(18,35,63,.075) 1px,transparent 1px),
    linear-gradient(90deg,rgba(18,35,63,.075) 1px,transparent 1px);
  background-size:56px 56px;
  background-position:center center;
}

@media (max-width:960px){
  .coord-field{background-size:36px 36px;}
}

/* 响应式图片容器：页面阶段把 img 或占位内容放进去 */
.img-frame{
  position:relative;
  display:block;
  overflow:hidden;
  border-radius:var(--r-lg);
  border:1px solid rgba(36,26,22,.08);
  background-color:var(--by-mist);
}
.img-frame>img{
  width:100%;
  height:100%;
  object-fit:cover;
  display:block;
}
.img-frame>figcaption{
  position:absolute;
  left:0;right:0;bottom:0;
  padding:14px 18px;
  font-size:13px;
  line-height:1.6;
  color:var(--by-paper);
  background:linear-gradient(180deg,rgba(12,26,46,0) 0%,rgba(12,26,46,.78) 100%);
}
.img-frame--16x9{aspect-ratio:16 / 9;}
.img-frame--4x3{aspect-ratio:4 / 3;}
.img-frame--3x2{aspect-ratio:3 / 2;}
.img-frame--1x1{aspect-ratio:1 / 1;}
.img-frame--21x9{aspect-ratio:21 / 9;}
.img-frame--tall{aspect-ratio:3 / 4;}

@supports not (aspect-ratio: 1 / 1){
  .img-frame--16x9,.img-frame--4x3,.img-frame--3x2,.img-frame--1x1,.img-frame--21x9,.img-frame--tall{
    min-height:220px;
  }
}

.copy-btn{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:7px 15px;
  border-radius:var(--r-pill);
  border:1.5px solid rgba(36,26,22,.2);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.06em;
  line-height:1.6;
  color:var(--by-slate);
  transition:color .2s var(--ease),
             border-color .2s var(--ease),
             background-color .2s var(--ease);
}
.copy-btn:hover{
  color:var(--by-red);
  border-color:var(--by-red);
}
.copy-btn.is-done{
  color:var(--by-green);
  border-color:var(--by-green);
  background:rgba(47,143,107,.08);
}

/* ---------- 9. 正文容器 ---------- */
.prose{
  max-width:68ch;
  font-size:17px;
  line-height:1.78;
  color:var(--by-ink);
}
.prose p+p{margin-top:1.05em;}
.prose h2{
  margin-top:1.9em;
  margin-bottom:.6em;
  font-size:clamp(22px,2.6vw,32px);
  font-weight:800;
  letter-spacing:-.01em;
}
.prose h3{
  margin-top:1.5em;
  margin-bottom:.5em;
  font-size:clamp(18px,2vw,22px);
  font-weight:700;
}
.prose ul,
.prose ol{
  margin-top:.9em;
  padding-left:1.4em;
  list-style:disc;
}
.prose ol{list-style:decimal;}
.prose li+li{margin-top:.45em;}
.prose a{
  color:var(--by-red);
  border-bottom:1px solid rgba(226,58,46,.4);
}
.prose a:hover{border-bottom-color:var(--by-red);}
.prose blockquote{
  margin-top:1.4em;
  padding:18px 22px;
  border-left:3px solid var(--by-sand);
  border-radius:0 var(--r-md) var(--r-md) 0;
  background:var(--by-paper);
  color:var(--by-ink);
}

/* ---------- 10. 显现动效 ---------- */
[data-reveal]{
  opacity:0;
  transform:translateY(12px);
  transition:opacity .55s var(--ease),transform .55s var(--ease);
  will-change:opacity,transform;
}
[data-reveal].is-visible{
  opacity:1;
  transform:none;
}

/* ---------- 11. 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;
  }

  [data-reveal]{
    opacity:1 !important;
    transform:none !important;
  }

  .skip-link{transition:none;}
}