/* ============================================================
   BG电子官网 · 共享样式 /assets/site.css
   轨道导航 + 海报式暗色体系
   ============================================================ */

:root{
  --ink:#0A1F44;
  --ink-deep:#061530;
  --panel:#122A57;
  --line:#24406F;
  --cyan:#00E5FF;
  --cyan-mist:#7CF3FF;
  --orange:#FF6B35;
  --orange-sand:#FFB199;
  --white:#EAF2FF;
  --muted:#9FB3D6;
  --paper:#F4F7FF;
  --dim:#3B5A8C;

  --rail-w:112px;
  --topbar-h:64px;
  --ease:cubic-bezier(.2,.7,.3,1);
  --gutter:clamp(20px,4vw,64px);
  --max-w:1400px;
  --cut-sm:10px;
  --cut-md:18px;

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

/* ---------- reset ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%}
body,h1,h2,h3,h4,h5,p,ul,ol,li,figure,blockquote,dl,dd{margin:0;padding:0}
ul[role="list"],.rail__list,.footer__list,.footer__legal-links{list-style:none}
img,svg,video{display:block;max-width:100%}
a{color:inherit}
button{font:inherit;color:inherit}
table{border-collapse:collapse;width:100%}
:where(a,button,summary,[tabindex]):focus-visible{
  outline:2px solid var(--cyan);
  outline-offset:3px;
}

/* ---------- 中文排版与基色 ---------- */
body{
  min-height:100vh;
  margin:0;
  padding-inline-start:var(--rail-w);
  padding-block-start:var(--topbar-h);
  font-family:var(--font-sans);
  font-size:clamp(15px,0.35vw + 14px,17px);
  font-weight:400;
  line-height:1.75;
  letter-spacing:0.01em;
  color:var(--white);
  background-color:var(--ink);
  background-image:
    radial-gradient(900px 560px at 88% -8%,rgba(0,229,255,.14),transparent 60%),
    radial-gradient(680px 480px at 2% 8%,rgba(255,107,53,.10),transparent 62%);
  background-repeat:no-repeat;
  -webkit-font-smoothing:antialiased;
}
body::before{
  content:"";
  position:fixed;
  inset:0;
  z-index:0;
  pointer-events:none;
  background-image:radial-gradient(rgba(36,64,111,.55) 1px,transparent 1px);
  background-size:26px 26px;
  opacity:.35;
}
h1,h2,h3,h4{
  font-weight:900;
  line-height:1.1;
  letter-spacing:-0.02em;
  text-wrap:balance;
  color:var(--white);
}
h1{font-size:clamp(40px,7vw,104px)}
h2{font-size:clamp(26px,3.4vw,44px)}
h3{font-size:clamp(19px,1.8vw,24px);line-height:1.3}
p{max-width:40em;color:var(--muted)}
strong{color:var(--white);font-weight:700}
a{text-decoration-color:rgba(0,229,255,.4)}
#main-content{display:block;scroll-margin-block-start:calc(var(--topbar-h) + 16px)}

/* ---------- 布局工具 ---------- */
.shell{
  width:100%;
  max-width:var(--max-w);
  margin-inline:auto;
  padding-inline:var(--gutter);
}
.mono{font-family:var(--font-mono);font-size:12px;letter-spacing:.08em}
.eyebrow{
  display:inline-flex;
  align-items:center;
  gap:10px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.24em;
  color:var(--cyan);
}
.eyebrow::before{
  content:"";
  display:block;
  width:28px;
  height:1px;
  background:var(--cyan);
}
.panel{
  position:relative;
  padding:clamp(20px,3vw,32px);
  background:var(--panel);
  border:1px solid var(--line);
  clip-path:polygon(0 0,calc(100% - var(--cut-md)) 0,100% var(--cut-md),100% 100%,var(--cut-md) 100%,0 calc(100% - var(--cut-md)));
}
.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:3px 10px;
  font-size:11px;
  letter-spacing:.1em;
  line-height:1.6;
  color:var(--ink-deep);
  background:var(--orange-sand);
  clip-path:polygon(var(--cut-sm) 0,100% 0,100% 100%,0 100%,0 var(--cut-sm));
}
.tag--cyan{
  color:var(--cyan);
  background:rgba(0,229,255,.14);
  border:1px solid rgba(0,229,255,.42);
}
.crumbs{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  color:var(--dim);
}
.crumbs a{color:var(--muted);text-decoration:none}
.crumbs a:hover{color:var(--cyan)}
.crumbs [aria-current="page"]{color:var(--cyan)}

/* ---------- 图片容器基础（页面阶段放置 img / 占位） ---------- */
.figure{
  position:relative;
  margin:0;
  isolation:isolate;
  overflow:hidden;
  background:linear-gradient(135deg,var(--panel) 0%,var(--ink-deep) 100%);
  border:1px solid var(--line);
  clip-path:polygon(0 0,calc(100% - 24px) 0,100% 24px,100% 100%,24px 100%,0 calc(100% - 24px));
}
.figure__media{
  display:block;
  width:100%;
  height:auto;
  aspect-ratio:16/9;
  object-fit:cover;
}
.figure__media--wide{aspect-ratio:21/9}
.figure__media--tall{aspect-ratio:4/5}
.figure__cap{
  display:flex;
  gap:10px;
  padding:12px 16px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.1em;
  color:var(--muted);
  border-block-start:1px solid var(--line);
  background:rgba(6,21,48,.6);
}

/* ---------- 按钮 ---------- */
.btn{
  --btn-bg:transparent;
  --btn-fg:var(--white);
  --btn-bd:var(--line);
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:.5em;
  min-height:40px;
  padding:.5em 1.05em;
  font-size:13px;
  font-weight:600;
  letter-spacing:.05em;
  line-height:1.4;
  text-decoration:none;
  white-space:nowrap;
  color:var(--btn-fg);
  background:var(--btn-bg);
  border:1px solid var(--btn-bd);
  cursor:pointer;
  clip-path:polygon(var(--cut-sm) 0,100% 0,100% calc(100% - var(--cut-sm)),calc(100% - var(--cut-sm)) 100%,0 100%,0 var(--cut-sm));
  transition:background .18s var(--ease),color .18s var(--ease),border-color .18s var(--ease),transform .18s var(--ease);
}
.btn:focus-visible{outline:none;box-shadow:inset 0 0 0 2px var(--cyan)}
.btn--solid{
  --btn-bg:var(--orange);
  --btn-fg:var(--ink-deep);
  --btn-bd:var(--orange);
  font-weight:700;
}
.btn--solid:hover{--btn-bg:var(--orange-sand);--btn-bd:var(--orange-sand);transform:translateY(-2px)}
.btn--line{
  --btn-bg:transparent;
  --btn-fg:var(--cyan);
  --btn-bd:rgba(0,229,255,.45);
}
.btn--line:hover{
  --btn-bg:rgba(0,229,255,.12);
  --btn-bd:var(--cyan);
  transform:translateY(-2px);
}

/* ---------- 跳转链接 ---------- */
.skip-link{
  position:fixed;
  inset-block-start:8px;
  inset-inline-start:calc(var(--rail-w) + 12px);
  z-index:200;
  padding:10px 18px;
  font-size:14px;
  font-weight:700;
  letter-spacing:.04em;
  color:var(--ink-deep);
  background:var(--cyan);
  text-decoration:none;
  transform:translateY(-180%);
  clip-path:polygon(8px 0,100% 0,100% 100%,0 100%,0 8px);
  transition:transform .2s var(--ease);
}
.skip-link:focus{transform:translateY(0)}

/* ---------- 头部骨架 ---------- */
.site-header{position:relative;z-index:90;margin:0;padding:0}

/* 左侧轨道 */
.rail-col{
  position:fixed;
  inset-block:0;
  inset-inline-start:0;
  z-index:80;
  width:var(--rail-w);
  background:linear-gradient(180deg,#0A1F44 0%,#061530 100%);
  border-inline-end:1px solid var(--line);
}
.rail{
  display:flex;
  flex-direction:column;
  justify-content:space-between;
  gap:24px;
  width:100%;
  height:100%;
  padding:16px 0 20px;
}
.rail__list{
  display:flex;
  flex-direction:column;
  gap:2px;
  width:100%;
}
.rail__item{width:100%}
.rail__link{
  position:relative;
  display:flex;
  flex-direction:column;
  align-items:center;
  gap:6px;
  padding:12px 6px;
  font-size:12px;
  font-weight:500;
  letter-spacing:.1em;
  line-height:1.4;
  text-align:center;
  text-decoration:none;
  color:var(--muted);
  border-inline-start:2px solid transparent;
  transition:color .18s var(--ease),background .18s var(--ease),border-color .18s var(--ease);
}
.rail__link:hover{
  color:var(--cyan-mist);
  background:rgba(0,229,255,.07);
  border-inline-start-color:rgba(0,229,255,.5);
}
.rail__link[aria-current="page"]{
  color:var(--orange);
  border-inline-start-color:var(--orange);
  background:linear-gradient(90deg,rgba(255,107,53,.18),rgba(255,107,53,0) 82%);
  font-weight:700;
}
.rail__num{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  color:var(--dim);
  transition:color .18s var(--ease);
}
.rail__link:hover .rail__num{color:var(--cyan)}
.rail__link[aria-current="page"] .rail__num{color:var(--orange-sand)}
.rail__text{display:block}
.rail__note{
  margin:0;
  padding:14px 10px 0;
  font-size:10px;
  line-height:1.6;
  letter-spacing:.06em;
  text-align:center;
  color:var(--dim);
  border-block-start:1px solid var(--line);
}

/* 顶部横条 */
.topbar{
  position:fixed;
  inset-block-start:0;
  inset-inline-start:var(--rail-w);
  inset-inline-end:0;
  z-index:70;
  display:flex;
  align-items:center;
  gap:clamp(10px,2vw,28px);
  height:var(--topbar-h);
  padding-inline:var(--gutter);
  background:rgba(6,21,48,.86);
  backdrop-filter:blur(12px);
  -webkit-backdrop-filter:blur(12px);
  border-block-end:1px solid var(--line);
}
.brand{
  display:inline-flex;
  align-items:center;
  gap:12px;
  margin-inline-end:auto;
  text-decoration:none;
  color:var(--white);
}
.brand__mark{
  padding:4px 10px 6px;
  font-size:21px;
  font-weight:900;
  letter-spacing:-.03em;
  line-height:1;
  color:var(--ink-deep);
  background:var(--cyan);
  clip-path:polygon(0 0,100% 0,100% 62%,86% 100%,0 100%);
  transition:background .18s var(--ease);
}
.brand:hover .brand__mark{background:var(--cyan-mist)}
.brand__sub{
  padding-inline-start:12px;
  font-size:11px;
  letter-spacing:.22em;
  color:var(--muted);
  border-inline-start:1px solid var(--line);
  transition:color .18s var(--ease);
}
.brand:hover .brand__sub{color:var(--cyan-mist)}
.topbar__actions{display:flex;align-items:center;gap:10px}

/* 汉堡按钮 */
.nav-toggle{
  display:none;
  align-items:center;
  gap:9px;
  min-height:40px;
  padding:6px 12px;
  font-size:12px;
  letter-spacing:.16em;
  color:var(--white);
  background:transparent;
  border:1px solid var(--line);
  cursor:pointer;
  clip-path:polygon(8px 0,100% 0,100% calc(100% - 8px),calc(100% - 8px) 100%,0 100%,0 8px);
  transition:border-color .18s var(--ease),background .18s var(--ease);
}
.nav-toggle:hover{border-color:var(--cyan);background:rgba(0,229,255,.08)}
.nav-toggle__bars{
  display:inline-flex;
  flex-direction:column;
  justify-content:center;
  gap:5px;
  width:18px;
  height:14px;
}
.nav-toggle__bar{
  display:block;
  height:2px;
  background:var(--cyan);
  border-radius:2px;
  transition:transform .2s var(--ease),opacity .2s var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1){transform:translateY(3.5px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2){transform:translateY(-3.5px) rotate(-45deg)}
.nav-toggle__label{display:block}

/* 移动遮罩 */
.nav-scrim{
  position:fixed;
  inset:0;
  z-index:85;
  background:rgba(4,16,31,.68);
  opacity:0;
  pointer-events:none;
  transition:opacity .25s var(--ease);
}
.nav-scrim[data-visible="true"]{opacity:1;pointer-events:auto}

/* 滚动进度 */
.scroll-bar{
  position:fixed;
  inset-block-start:var(--topbar-h);
  inset-inline-start:var(--rail-w);
  inset-inline-end:0;
  z-index:75;
  height:2px;
  background:rgba(36,64,111,.45);
  pointer-events:none;
}
.scroll-bar__fill{
  display:block;
  width:100%;
  height:100%;
  transform:scaleX(0);
  transform-origin:0 50%;
  background:linear-gradient(90deg,var(--cyan),var(--cyan-mist) 58%,var(--orange));
}

/* ---------- 页脚 ---------- */
.site-footer{
  position:relative;
  z-index:1;
  margin-block-start:clamp(64px,9vw,140px);
  background:linear-gradient(180deg,#0A1F44 0%,#061530 46%,#04101f 100%);
  border-block-start:1px solid var(--line);
}
.site-footer::before{
  content:"";
  position:absolute;
  inset-block-start:-1px;
  inset-inline:0;
  height:3px;
  background:linear-gradient(90deg,var(--cyan) 0 18%,var(--line) 18% 72%,var(--orange) 72% 100%);
}
.footer__inner{
  display:grid;
  grid-template-columns:minmax(220px,1.05fr) 1.55fr 1fr;
  gap:clamp(28px,4vw,64px);
  max-width:var(--max-w);
  margin-inline:auto;
  padding:clamp(44px,6vw,80px) var(--gutter) clamp(32px,4vw,52px);
}
.footer__brand{display:flex;flex-direction:column;align-items:flex-start;gap:14px}
.footer__word{
  font-size:clamp(30px,3.6vw,50px);
  font-weight:900;
  letter-spacing:-.03em;
  line-height:1;
  color:var(--white);
}
.footer__word span{color:var(--cyan)}
.footer__tagline{
  max-width:24ch;
  margin:0;
  font-size:14px;
  line-height:1.7;
  color:var(--muted);
}
.footer__cols{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:clamp(16px,2vw,32px);
}
.footer__col{min-width:0}
.footer__h{
  margin-block-end:16px;
  font-family:var(--font-mono);
  font-size:11px;
  font-weight:700;
  letter-spacing:.28em;
  color:var(--dim);
}
.footer__list{display:grid;gap:10px}
.footer__link{
  display:inline-block;
  padding-block:2px;
  font-size:14px;
  color:var(--muted);
  text-decoration:none;
  border-block-end:1px solid transparent;
  transition:color .18s var(--ease),border-color .18s var(--ease),transform .18s var(--ease);
}
.footer__link:hover{
  color:var(--cyan-mist);
  border-block-end-color:var(--cyan);
  transform:translateX(3px);
}
.footer__contact{display:grid;align-content:start;gap:10px}
.footer__row{
  display:flex;
  flex-wrap:wrap;
  align-items:baseline;
  gap:6px 10px;
  max-width:none;
  font-size:13px;
  color:var(--muted);
}
.footer__row--wide{align-items:flex-start}
.footer__label{
  flex:0 0 auto;
  min-width:34px;
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.18em;
  color:var(--dim);
}
.footer__value{
  flex:1 1 auto;
  min-width:0;
  font-size:13.5px;
  line-height:1.65;
  color:var(--white);
  word-break:break-word;
}
.footer__value--mono{font-family:var(--font-mono);letter-spacing:.05em}
.copy-btn{
  flex:0 0 auto;
  padding:2px 8px;
  font-family:var(--font-mono);
  font-size:10px;
  letter-spacing:.14em;
  color:var(--muted);
  background:transparent;
  border:1px solid var(--line);
  cursor:pointer;
  transition:color .18s var(--ease),border-color .18s var(--ease),background .18s var(--ease);
}
.copy-btn:hover{color:var(--cyan);border-color:var(--cyan);background:rgba(0,229,255,.08)}
.copy-btn[data-copied="true"]{color:var(--ink-deep);background:var(--cyan);border-color:var(--cyan)}
.footer__meta{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:12px 24px;
  max-width:var(--max-w);
  margin-inline:auto;
  padding:18px var(--gutter) 34px;
  border-block-start:1px solid var(--line);
  font-size:12px;
  letter-spacing:.04em;
  color:var(--dim);
}
.footer__legal{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:6px 12px;
  max-width:none;
  font-size:12px;
  color:var(--dim);
}
.footer__legal-sep{color:var(--line)}
.footer__icp{font-family:var(--font-mono);letter-spacing:.06em}
.footer__legal-links{display:flex;flex-wrap:wrap;gap:6px 20px}
.footer__legal-links a{
  color:var(--muted);
  text-decoration:none;
  transition:color .18s var(--ease);
}
.footer__legal-links a:hover{color:var(--cyan)}

/* ---------- 显现（JS 写入 data-in） ---------- */
[data-reveal]{transition:opacity .55s var(--ease),transform .55s var(--ease)}
html[data-js="true"] [data-reveal]:not([data-in]){
  opacity:0;
  transform:translateY(12px);
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width:1100px){
  .footer__inner{grid-template-columns:minmax(200px,1fr) 1.4fr;row-gap:40px}
  .footer__contact{grid-column:1/-1}
}

@media (max-width:899px){
  :root{--rail-w:0px;--topbar-h:60px}

  body{padding-inline-start:0}
  .rail-col{position:static;width:0;background:none;border:0}

  .rail{
    position:fixed;
    inset-block:0;
    inset-inline-start:0;
    z-index:95;
    width:min(84vw,320px);
    height:100vh;
    padding:calc(var(--topbar-h) + 20px) 18px 28px;
    gap:18px;
    overflow-y:auto;
    background:linear-gradient(180deg,#122A57 0%,#061530 78%);
    border-inline-end:1px solid var(--cyan);
    box-shadow:0 0 0 1px rgba(0,229,255,.18);
    transform:translateX(-104%);
    transition:transform .3s var(--ease);
  }
  .rail[data-open="true"]{transform:translateX(0)}

  .rail__list{gap:4px}
  .rail__link{
    flex-direction:row;
    align-items:center;
    justify-content:flex-start;
    gap:14px;
    padding:13px 12px;
    font-size:15px;
    letter-spacing:.06em;
    text-align:start;
    border-inline-start-width:2px;
    border-block-end:1px solid rgba(36,64,111,.6);
  }
  .rail__num{font-size:12px}
  .rail__note{
    padding:16px 4px 0;
    font-size:11px;
    line-height:1.7;
    text-align:start;
    color:var(--muted);
    border-block-start:1px solid var(--line);
  }

  .nav-toggle{display:inline-flex}
  .skip-link{inset-inline-start:12px}

  .footer__cols{grid-template-columns:repeat(3,minmax(0,1fr))}
}

@media (max-width:760px){
  .footer__inner{grid-template-columns:1fr;gap:36px}
  .footer__contact{grid-column:auto}
  .footer__cols{grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
  .footer__tagline{max-width:36ch}
}

@media (max-width:640px){
  .topbar .btn--line{display:none}
  .brand__sub{display:none}
  .footer__cols{grid-template-columns:1fr 1fr}
  .footer__legal-links{gap:6px 16px}
  .panel{clip-path:polygon(0 0,calc(100% - 12px) 0,100% 12px,100% 100%,12px 100%,0 calc(100% - 12px))}
  .figure{clip-path:polygon(0 0,calc(100% - 16px) 0,100% 16px,100% 100%,16px 100%,0 calc(100% - 16px))}
}

@media (max-width:420px){
  .footer__cols{grid-template-columns:1fr}
  .btn{min-height:38px;font-size:12px}
}

/* ---------- 减弱动效 ---------- */
@media (prefers-reduced-motion:reduce){
  *,
  *::before,
  *::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  html{scroll-behavior:auto !important}
  .rail{transition:none !important}
  .nav-scrim{transition:none !important}
  html[data-js="true"] [data-reveal]:not([data-in]){opacity:1;transform:none}
}