/* ==========================================================
   博赢BY · /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 页头 / 页脚 / 基础组件
   ========================================================== */

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

/* ---------- 2. 变量 ---------- */
:root{
  --ink-900:#061A24;
  --ink-800:#0B2A38;
  --ink-700:#123A4C;
  --paper:#F4EFE6;
  --paper-2:#E6DDCE;
  --cyan:#25F0E0;
  --gold:#D9A441;
  --gray:#6B7A85;
  --gray-2:#A8B4BC;
  --white:#F8FAFB;
  --alert:#E05A4F;
  --line-cool:rgba(168,180,188,.28);
  --line-cyan:rgba(37,240,224,.35);
  --font-head:"Inter","Source Han Sans SC","Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Source Han Sans SC","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono","IBM Plex Mono","SFMono-Regular",Menlo,Consolas,"Courier New",monospace;
  --font-editorial:"Playfair Display",Georgia,"Songti SC",serif;
  --shell:1280px;
  --gutter:22px;
  --frame-top:116px;
  --radius:2px;
}
@media (max-width:1100px){:root{--gutter:18px}}
@media (max-width:980px){:root{--frame-top:74px;--gutter:16px}}

/* ---------- 3. 基础排版 ---------- */
body{
  background:var(--ink-900);
  color:var(--paper);
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.6;
  padding-top:var(--frame-top);
  min-height:100vh;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,h4{font-family:var(--font-head);font-weight:800;line-height:1.15;letter-spacing:.01em;color:var(--white)}
h1{font-size:clamp(28px,4.6vw,52px)}
h2{font-size:clamp(22px,3vw,34px)}
h3{font-size:clamp(17px,2vw,21px)}
p{font-size:16px}
.mono{font-family:var(--font-mono);letter-spacing:.06em}
.eyebrow{display:block;font-family:var(--font-mono);font-size:12px;letter-spacing:.22em;text-transform:uppercase;color:var(--cyan)}
.lede{font-size:clamp(15px,1.6vw,17.5px);line-height:1.78;color:#CFD8DD}
#main-content{display:block;min-height:52vh}

/* ---------- 4. 可访问性 ---------- */
:focus-visible{outline:2px solid var(--cyan);outline-offset:3px}
.skip-link{
  position:fixed;top:10px;left:10px;z-index:200;
  padding:10px 18px;border-radius:var(--radius);
  background:var(--cyan);color:#04222B;
  font-family:var(--font-head);font-weight:700;font-size:14px;
  transform:translateY(-180%);
}
.skip-link:focus-visible{transform:none}
.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.rule{border:0;height:1px;background:var(--line-cool);margin:32px 0}

/* ---------- 5. 页头（框架式导航） ---------- */
.site-header{
  position:fixed;top:0;left:0;right:0;z-index:90;
  background:linear-gradient(180deg,rgba(6,26,36,.98),rgba(11,42,56,.94));
  border-bottom:1px solid var(--line-cyan);
  box-shadow:0 1px 0 rgba(217,164,65,.22);
  -webkit-backdrop-filter:blur(12px);
  backdrop-filter:blur(12px);
}
.site-header::before{
  content:"";position:absolute;top:0;left:0;width:132px;height:3px;
  background:linear-gradient(90deg,var(--gold),rgba(217,164,65,0));
}
.site-header__inner{
  position:relative;
  width:min(var(--shell),100% - (var(--gutter) * 2));
  margin-inline:auto;
  display:grid;
  align-items:center;
  gap:0 20px;
  grid-template-columns:minmax(0,auto) minmax(0,1fr) auto;
  grid-template-areas:
    "brand brand meta"
    "nav nav nav";
}
.brand{grid-area:brand;display:flex;align-items:center;padding:12px 0 10px}
.brand__link{display:flex;flex-direction:column;gap:3px}
.brand__mark{
  font-family:var(--font-head);font-weight:800;font-size:22px;letter-spacing:.06em;
  color:var(--white);transition:color .18s ease;
}
.brand__link:hover .brand__mark,.brand__link:focus-visible .brand__mark{color:var(--cyan)}
.brand__line{font-size:12px;letter-spacing:.08em;color:var(--gray-2)}

.header-meta{
  grid-area:meta;display:flex;align-items:center;justify-content:flex-end;
  flex-wrap:wrap;gap:14px;padding:12px 0 10px;
}
.version-badge{
  display:inline-flex;align-items:center;gap:8px;
  padding:5px 11px;border:1px solid rgba(217,164,65,.6);
  background:rgba(217,164,65,.08);
  transition:background-color .18s ease,border-color .18s ease;
}
.version-badge__tag{font-size:11px;letter-spacing:.1em;color:var(--gray-2)}
.version-badge__num{font-family:var(--font-mono);font-size:14px;font-weight:700;color:var(--gold)}
.version-badge:hover,.version-badge:focus-visible{background:rgba(217,164,65,.18);border-color:var(--gold)}
.header-utility{display:flex;align-items:center;gap:16px}
.header-utility__item{display:block}
.header-utility__link{
  display:inline-block;padding:2px 0;font-size:13px;letter-spacing:.04em;
  color:var(--gray-2);border-bottom:1px solid transparent;
  transition:color .18s ease,border-color .18s ease;
}
.header-utility__link:hover,.header-utility__link:focus-visible{color:var(--cyan);border-bottom-color:var(--cyan)}
.header-cta{white-space:nowrap}

.nav-toggle{
  grid-area:toggle;display:none;align-items:center;gap:9px;
  padding:8px 12px;border:1px solid var(--line-cyan);color:var(--cyan);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.14em;cursor:pointer;
  transition:background-color .18s ease,border-color .18s ease;
}
.nav-toggle:hover{background:rgba(37,240,224,.1)}
.nav-toggle__bars{position:relative;display:inline-block;width:16px;height:10px}
.nav-toggle__bars::before,.nav-toggle__bars::after{
  content:"";position:absolute;left:0;right:0;height:1.5px;background:currentColor;
  transition:transform .18s ease,top .18s ease,bottom .18s ease;
}
.nav-toggle__bars::before{top:0}
.nav-toggle__bars::after{bottom:0}
.site-header[data-open] .nav-toggle__bars::before{top:4px;transform:rotate(45deg)}
.site-header[data-open] .nav-toggle__bars::after{bottom:4px;transform:rotate(-45deg)}

.site-nav{grid-area:nav}
.site-nav__list{
  display:flex;flex-wrap:wrap;
  border-top:1px solid var(--line-cool);
  counter-reset:nav;
}
.site-nav__item{counter-increment:nav}
.site-nav__link{
  display:flex;align-items:center;gap:8px;
  padding:12px 18px 13px;
  font-family:var(--font-head);font-weight:700;font-size:14px;letter-spacing:.05em;
  color:var(--paper);border-bottom:2px solid transparent;border-left:2px solid transparent;
  transition:color .18s ease,background-color .18s ease,border-color .18s ease;
}
.site-nav__link::before{
  content:counter(nav,decimal-leading-zero);
  font-family:var(--font-mono);font-size:11px;letter-spacing:.08em;
  color:var(--gold);opacity:.8;
}
.site-nav__link:hover,.site-nav__link:focus-visible{color:var(--cyan);background:rgba(37,240,224,.06);border-bottom-color:rgba(37,240,224,.5)}
.site-nav__link[aria-current="page"]{color:var(--cyan);background:rgba(37,240,224,.09);border-bottom-color:var(--cyan)}
.site-nav__link[aria-current="page"]::before{color:var(--cyan);opacity:1}

.scroll-progress{
  position:absolute;left:0;right:0;bottom:-1px;height:2px;
  background:linear-gradient(90deg,var(--cyan),var(--gold));
  transform:scaleX(0);transform-origin:0 50%;
  transition:transform .15s linear;pointer-events:none;
}

/* 视口左缘的框架刻度（≥981px 生效） */
@media (min-width:981px){
  body::before{
    content:"";position:fixed;left:0;top:var(--frame-top);bottom:0;width:1px;z-index:80;
    background:linear-gradient(180deg,rgba(217,164,65,.75),rgba(37,240,224,.45) 22%,rgba(37,240,224,0));
    pointer-events:none;
  }
  body::after{
    content:"";position:fixed;left:0;top:calc(var(--frame-top) + 24px);bottom:24px;width:9px;z-index:80;
    background-image:repeating-linear-gradient(180deg,rgba(37,240,224,.32) 0 1px,transparent 1px 34px);
    pointer-events:none;
  }
}

/* ---------- 6. 页脚 ---------- */
.site-footer{
  position:relative;
  background:var(--ink-900);
  border-top:1px solid var(--line-cyan);
  color:var(--paper);
}
.site-footer::before{
  content:"";position:absolute;top:0;left:0;width:132px;height:3px;
  background:linear-gradient(90deg,var(--gold),rgba(217,164,65,0));
}
.site-footer__inner{
  width:min(var(--shell),100% - (var(--gutter) * 2));
  margin-inline:auto;padding:60px 0 26px;
}
.site-footer__grid{
  display:grid;gap:36px 32px;
  grid-template-columns:minmax(0,1.5fr) minmax(0,1fr) minmax(0,1fr) minmax(0,1.4fr);
}
.footer-brand__mark{
  font-family:var(--font-head);font-weight:800;font-size:24px;letter-spacing:.06em;color:var(--white);
}
.footer-brand__summary{margin-top:12px;font-size:14px;line-height:1.75;color:var(--gray-2);max-width:38ch}
.footer-brand__note{
  margin-top:14px;font-family:var(--font-mono);font-size:11.5px;letter-spacing:.1em;color:var(--gold);
}
.footer-group__title{
  font-family:var(--font-head);font-size:13px;font-weight:700;letter-spacing:.16em;
  color:var(--white);text-transform:uppercase;
  padding-bottom:10px;margin-bottom:12px;border-bottom:1px solid var(--line-cool);
}
.footer-group__list{display:grid;gap:9px}
.footer-group__link{
  display:inline-block;font-size:14px;color:var(--gray-2);
  border-bottom:1px solid transparent;transition:color .18s ease,border-color .18s ease,padding-left .18s ease;
}
.footer-group__link:hover,.footer-group__link:focus-visible{color:var(--cyan);border-bottom-color:var(--cyan);padding-left:4px}
.footer-contact__list{display:grid}
.footer-contact__row{
  display:grid;grid-template-columns:84px minmax(0,1fr) auto;gap:10px;align-items:center;
  padding:10px 0;border-bottom:1px solid rgba(168,180,188,.16);
}
.footer-contact__key{font-family:var(--font-mono);font-size:11px;letter-spacing:.14em;color:var(--gray-2)}
.footer-contact__val{font-size:14px;color:var(--white);word-break:break-all}
.footer-contact__note{margin-top:14px;font-size:12.5px;line-height:1.7;color:var(--gray)}
.copy-btn{
  display:inline-flex;align-items:center;gap:6px;
  padding:4px 9px;border:1px solid rgba(168,180,188,.45);color:var(--gray-2);
  font-family:var(--font-mono);font-size:11px;letter-spacing:.12em;cursor:pointer;
  transition:border-color .18s ease,color .18s ease,background-color .18s ease;
}
.copy-btn:hover,.copy-btn:focus-visible{border-color:var(--cyan);color:var(--cyan)}
.copy-btn[data-copied]{border-color:var(--gold);color:var(--gold);background:rgba(217,164,65,.12)}
.site-footer__bottom{
  display:flex;flex-wrap:wrap;justify-content:space-between;align-items:baseline;gap:8px 24px;
  margin-top:46px;padding-top:18px;border-top:1px solid rgba(168,180,188,.2);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.06em;color:var(--gray-2);
}
.site-footer__legal{color:var(--gray-2)}
.site-footer__copy{max-width:62ch}

/* ---------- 7. 布局容器与色带 ---------- */
.shell{width:min(var(--shell),100% - (var(--gutter) * 2));margin-inline:auto}
.section{padding:76px 0}
.section--tight{padding:44px 0}
.band{position:relative;background:var(--ink-800);color:var(--paper)}
.band--deep{background:var(--ink-900)}
.band--ink{background:var(--ink-800)}
.band--paper{background:var(--paper);color:var(--ink-800)}
.band--paper-2{background:var(--paper-2);color:var(--ink-800)}
.band--glass{
  background:rgba(11,42,56,.55);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
  border-top:1px solid var(--line-cyan);
  border-bottom:1px solid var(--line-cyan);
}
.band--paper h1,.band--paper h2,.band--paper h3,.band--paper h4,
.band--paper-2 h1,.band--paper-2 h2,.band--paper-3 h3{color:var(--ink-800)}
.band--paper p,.band--paper li,.band--paper-2 p,.band--paper-2 li{color:#33454F}
.band--paper .lede,.band--paper-2 .lede{color:#33454F}
.band--paper .eyebrow,.band--paper-2 .eyebrow{color:#0F7A73}
.band--paper a:not(.btn),.band--paper-2 a:not(.btn){color:#0E6E68}
.band--paper .section-head__note,.band--paper-2 .section-head__note{color:var(--gray)}
.band--paper .section-head,.band--paper-2 .section-head{border-bottom-color:rgba(107,122,133,.35)}
.band--paper .section-head__num,.band--paper-2 .section-head__num{color:#9A7526}

/* ---------- 8. 章节刊头与面板 ---------- */
.section-head{
  display:flex;flex-wrap:wrap;align-items:baseline;gap:10px 18px;
  padding-bottom:14px;margin-bottom:28px;border-bottom:1px solid var(--line-cool);
}
.section-head__num{font-family:var(--font-mono);font-size:12px;letter-spacing:.2em;color:var(--gold)}
.section-head__title{font-family:var(--font-head);font-weight:800;font-size:clamp(21px,2.8vw,30px);color:inherit}
.section-head__note{margin-left:auto;font-size:13px;color:var(--gray-2)}
.band--paper .section-head__title,.band--paper-2 .section-head__title{color:var(--ink-800)}
.glass{
  background:rgba(11,42,56,.55);
  border:1px solid var(--line-cyan);
  -webkit-backdrop-filter:blur(8px);
  backdrop-filter:blur(8px);
  padding:22px;
}
.paper-panel{background:var(--paper);color:var(--ink-800);border:1px solid var(--paper-2);padding:24px}
.paper-panel h2,.paper-panel h3{color:var(--ink-800)}
.paper-panel p{color:#33454F}

/* ---------- 9. 索引网格与卡片矩阵 ---------- */
.index-grid{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(238px,1fr));gap:1px;
  background:var(--line-cool);border:1px solid var(--line-cool);
}
.index-item{
  display:flex;flex-direction:column;gap:8px;
  padding:20px 20px 22px;background:var(--ink-800);
  transition:background-color .18s ease;
}
.index-item:hover{background:var(--ink-700)}
.index-item__tag{font-family:var(--font-mono);font-size:11px;letter-spacing:.16em;color:var(--gold)}
.index-item__title{font-family:var(--font-head);font-weight:700;font-size:17px;line-height:1.3;color:var(--white)}
.index-item__text{font-size:13.5px;line-height:1.68;color:var(--gray-2)}
.band--paper .index-grid,.band--paper-2 .index-grid{background:var(--paper-2);border-color:var(--paper-2)}
.band--paper .index-item,.band--paper-2 .index-item{background:var(--paper)}
.band--paper .index-item:hover,.band--paper-2 .index-item:hover{background:var(--paper-2)}
.band--paper .index-item__title,.band--paper-2 .index-item__title{color:var(--ink-800)}
.band--paper .index-item__text,.band--paper-2 .index-item__text{color:var(--gray)}
.band--paper .index-item__tag,.band--paper-2 .index-item__tag{color:#9A7526}

.grid{display:grid;gap:22px}
.grid--2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--4{grid-template-columns:repeat(4,minmax(0,1fr))}
.stagger>*{margin-top:0}
@media (min-width:1041px){
  .stagger>*:nth-child(even){margin-top:34px}
}
@media (max-width:1040px){
  .grid--3,.grid--4{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (max-width:680px){
  .grid--2,.grid--3,.grid--4{grid-template-columns:minmax(0,1fr)}
  .stagger>*{margin-top:0}
}

/* ---------- 10. 标签、按钮、面包屑 ---------- */
.tag{
  display:inline-flex;align-items:center;gap:6px;
  padding:3px 8px;border:1px solid var(--line-cool);
  font-family:var(--font-mono);font-size:11px;letter-spacing:.12em;color:var(--gray-2);
}
.tag--cyan{color:var(--cyan);border-color:var(--line-cyan)}
.tag--gold{color:var(--gold);border-color:rgba(217,164,65,.55)}
.tag--alert{color:var(--alert);border-color:rgba(224,90,79,.55)}

.btn{
  display:inline-flex;align-items:center;gap:10px;
  padding:12px 20px;border:1px solid transparent;border-radius:var(--radius);
  font-family:var(--font-head);font-weight:700;font-size:14px;letter-spacing:.05em;
  cursor:pointer;text-align:center;
  transition:background-color .18s ease,color .18s ease,border-color .18s ease;
}
.btn--sm{padding:8px 14px;font-size:13px}
.btn--primary{background:var(--gold);border-color:var(--gold);color:#132029}
.btn--primary:hover,.btn--primary:focus-visible{background:#E9B656;border-color:#E9B656;color:#0B1A22}
.btn--ghost{border-color:rgba(37,240,224,.55);color:var(--cyan)}
.btn--ghost:hover,.btn--ghost:focus-visible{background:rgba(37,240,224,.12);border-color:var(--cyan)}
.btn--quiet{border-color:rgba(168,180,188,.45);color:var(--paper)}
.btn--quiet:hover,.btn--quiet:focus-visible{border-color:var(--white);color:var(--white)}

.breadcrumb{padding:18px 0 0}
.breadcrumb__list{display:flex;flex-wrap:wrap;gap:8px;font-family:var(--font-mono);font-size:12px;letter-spacing:.06em}
.breadcrumb__item{display:flex;align-items:center;gap:8px;color:var(--gray-2)}
.breadcrumb__item + .breadcrumb__item::before{content:"/";color:#4C5F6A}
.breadcrumb__link{color:var(--gray-2);border-bottom:1px solid transparent;transition:color .18s ease,border-color .18s ease}
.breadcrumb__link:hover,.breadcrumb__link:focus-visible{color:var(--cyan);border-bottom-color:var(--cyan)}
.breadcrumb__current{color:var(--paper)}

/* ---------- 11. 图片容器（页面阶段放置图片） ---------- */
.media-frame{
  position:relative;overflow:hidden;aspect-ratio:16/10;
  border:1px solid var(--line-cool);background:var(--ink-900);
}
.media-frame__img{width:100%;height:100%;object-fit:cover}
.media-frame__caption{
  margin-top:10px;font-family:var(--font-mono);font-size:11.5px;letter-spacing:.08em;color:var(--gray-2);
}
.media-frame--tall{aspect-ratio:3/4}
.media-frame--wide{aspect-ratio:21/9}
.media-frame__placeholder{
  position:absolute;inset:0;
  background-image:
    linear-gradient(135deg,rgba(37,240,224,.14),rgba(217,164,65,.12)),
    repeating-linear-gradient(0deg,rgba(168,180,188,.16) 0 1px,transparent 1px 28px),
    repeating-linear-gradient(90deg,rgba(168,180,188,.16) 0 1px,transparent 1px 28px);
}
@media (max-width:680px){
  .media-frame{aspect-ratio:4/3}
  .media-frame--wide{aspect-ratio:16/10}
}

/* ---------- 12. 键值信息表 ---------- */
.meta-list{display:grid;gap:1px;background:var(--line-cool);border:1px solid var(--line-cool)}
.meta-list__row{
  display:grid;grid-template-columns:150px minmax(0,1fr);gap:14px;align-items:center;
  padding:12px 16px;background:var(--ink-800);
}
.meta-list__key{font-family:var(--font-mono);font-size:11px;letter-spacing:.14em;color:var(--gray-2);text-transform:uppercase}
.meta-list__val{font-size:14.5px;color:var(--white);word-break:break-word}
@media (max-width:560px){
  .meta-list__row{grid-template-columns:minmax(0,1fr);gap:4px}
}

/* ---------- 13. 响应式：≤980px 移动导航 ---------- */
@media (max-width:980px){
  .site-header__inner{
    grid-template-columns:minmax(0,1fr) auto;
    grid-template-areas:
      "brand toggle"
      "meta meta"
      "nav nav";
    gap:0 14px;
  }
  .brand{padding:10px 0}
  .brand__mark{font-size:19px}
  .brand__line{font-size:11px;letter-spacing:.06em}
  .nav-toggle{display:inline-flex}
  .header-meta{
    display:none;justify-content:flex-start;flex-wrap:wrap;gap:12px;
    padding:12px 0 14px;border-top:1px solid var(--line-cool);
  }
  .site-nav{display:none}
  .site-header[data-open] .header-meta{display:flex}
  .site-header[data-open] .site-nav{display:block;padding-bottom:10px}
  .site-nav__list{flex-direction:column;border-top:0}
  .site-nav__item{width:100%}
  .site-nav__link{
    justify-content:flex-start;
    padding:13px 2px;font-size:15px;
    border-bottom:1px solid rgba(168,180,188,.18);
  }
  .site-nav__link:hover,.site-nav__link:focus-visible{border-bottom-color:rgba(37,240,224,.45);border-left-color:var(--cyan)}
  .site-nav__link[aria-current="page"]{border-bottom-color:rgba(37,240,224,.4);border-left-color:var(--cyan)}
  .header-cta{width:100%;justify-content:center}
  .site-footer__grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:32px 24px}
  .footer-brand{grid-column:1 / -1}
}
@media (max-width:640px){
  .site-footer__inner{padding:44px 0 22px}
  .site-footer__grid{grid-template-columns:minmax(0,1fr);gap:28px}
  .footer-contact__row{grid-template-columns:minmax(0,1fr) auto;row-gap:6px}
  .footer-contact__key{grid-column:1 / -1}
  .site-footer__bottom{margin-top:34px}
  .section{padding:56px 0}
  .section--tight{padding:36px 0}
  .section-head__note{margin-left:0;flex-basis:100%}
}

/* ---------- 14. 降低动效 ---------- */
@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-progress{transition:none}
}