/* ===== 开元棋盘主站 · 共享样式 /assets/site.css ===== */

:root{
  --ink:#0E0F0C;
  --walnut:#3A2A20;
  --stone:#8A8C86;
  --cream:#F2EDE4;
  --moss:#4F5D3A;
  --clay:#A65A3A;
  --gold:#C9A227;
  --cinnabar:#B03A2E;
  --jade:#2F8F83;
  --jade-lt:#7FD3C6;
  --night:#2A3038;
  --line:rgba(138,140,134,.32);
  --line-soft:rgba(138,140,134,.16);
  --line-cream:rgba(242,237,228,.14);
  --font-display:"Noto Sans SC","Source Han Sans SC","PingFang SC","HarmonyOS Sans SC","Microsoft YaHei",sans-serif;
  --font-body:"Noto Sans SC","Source Han Sans SC","PingFang SC","HarmonyOS Sans SC","Microsoft YaHei",sans-serif;
  --font-mono:"JetBrains Mono","IBM Plex Mono",ui-monospace,SFMono-Regular,Consolas,"Courier New",monospace;
  --wrap:1280px;
  --gut:clamp(18px,4vw,48px);
  --header-h:68px;
  --bar-h:54px;
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{
  margin:0;
  padding-bottom:calc(var(--bar-h) + env(safe-area-inset-bottom,0px));
  background:var(--ink);
  color:var(--cream);
  font-family:var(--font-body);
  font-size:17px;
  line-height:1.8;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
}
img,svg,video{display:block;max-width:100%;height:auto}
h1,h2,h3,h4,h5,h6,p,figure,blockquote,dl,dd{margin:0}
ul,ol{margin:0;padding:0;list-style:none}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;cursor:pointer}
table{border-collapse:collapse;width:100%}
:focus-visible{outline:2px solid var(--jade-lt);outline-offset:3px;border-radius:2px}
#main-content,[data-toc-section]{scroll-margin-top:112px}

/* ===== 版面工具 ===== */
.wrap{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gut)}
.mono{font-family:var(--font-mono);font-size:13px;letter-spacing:.06em}
.coord{font-family:var(--font-mono);font-size:12px;letter-spacing:.14em;color:var(--stone)}
.eyebrow{font-family:var(--font-mono);font-size:12px;letter-spacing:.22em;color:var(--gold);text-transform:uppercase}
.section{padding-block:clamp(48px,7vw,96px)}
.section--walnut{background:var(--walnut)}
.section--night{background:var(--night)}
.section--moss{background:var(--moss);color:var(--cream)}
.section--grid{
  background-image:linear-gradient(var(--line-soft) 1px,transparent 1px),linear-gradient(90deg,var(--line-soft) 1px,transparent 1px);
  background-size:64px 64px;
}
.grid-field{
  background-image:linear-gradient(var(--line-soft) 1px,transparent 1px),linear-gradient(90deg,var(--line-soft) 1px,transparent 1px);
  background-size:64px 64px;
}
.star-field{
  background-image:
    radial-gradient(circle at 14px 22px,rgba(242,237,228,.34) 1px,transparent 1.6px),
    radial-gradient(circle at 88px 70px,rgba(201,162,39,.42) 1.2px,transparent 1.8px),
    radial-gradient(circle at 46px 108px,rgba(127,211,198,.30) 1px,transparent 1.5px);
  background-size:130px 130px;
}
.grid{display:grid;gap:clamp(18px,2.4vw,32px)}
.grid--2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--5-7{grid-template-columns:minmax(0,5fr) minmax(0,7fr)}
.grid--4-8{grid-template-columns:minmax(0,4fr) minmax(0,8fr)}
.prose{max-width:68ch}
.prose > * + *{margin-top:1.1em}
.prose h2{font-family:var(--font-display);font-size:clamp(24px,3vw,34px);line-height:1.3;letter-spacing:-.01em;margin-top:1.8em}
.prose h3{font-family:var(--font-display);font-size:clamp(19px,2.2vw,24px);line-height:1.4;margin-top:1.6em}
.prose a{color:var(--jade-lt);border-bottom:1px solid rgba(127,211,198,.42)}
.prose ul{list-style:none}
.prose li{position:relative;padding-left:20px}
.prose li::before{content:"";position:absolute;left:2px;top:.85em;width:7px;height:1px;background:var(--gold)}

/* ===== 按钮 ===== */
.btn{
  display:inline-flex;align-items:center;gap:10px;
  padding:13px 24px;border:1px solid var(--gold);background:transparent;
  color:var(--gold);font-size:15px;letter-spacing:.06em;
  transition:background .25s ease,color .25s ease,border-color .25s ease;
}
.btn:hover{background:var(--gold);color:var(--ink)}
.btn--solid{background:var(--gold);color:var(--ink)}
.btn--solid:hover{background:var(--cream);border-color:var(--cream)}
.btn--jade{border-color:var(--jade);color:var(--jade-lt)}
.btn--jade:hover{background:var(--jade);border-color:var(--jade-lt);color:#06201D}
.btn--ghost{border-color:var(--line);color:var(--cream)}
.btn--ghost:hover{background:rgba(242,237,228,.08);border-color:var(--cream);color:var(--cream)}

/* ===== 面包屑 ===== */
.breadcrumb{display:flex;flex-wrap:wrap;align-items:center;gap:8px;padding-top:20px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--stone)}
.breadcrumb a{color:var(--stone);transition:color .25s ease}
.breadcrumb a:hover{color:var(--gold)}
.breadcrumb__sep{color:rgba(138,140,134,.5)}

/* ===== 图片容器 ===== */
.media{position:relative;overflow:hidden;background:var(--night);border:1px solid var(--line-soft)}
.media img{width:100%;height:100%;object-fit:cover}
.media--square{aspect-ratio:1/1}
.media--wide{aspect-ratio:16/9}
.media--portrait{aspect-ratio:3/4}
.media--board{
  background-image:
    linear-gradient(rgba(242,237,228,.07) 1px,transparent 1px),
    linear-gradient(90deg,rgba(242,237,228,.07) 1px,transparent 1px);
  background-size:32px 32px;
}
.media__caption{
  padding:10px 14px;border-top:1px solid var(--line-soft);
  background:rgba(14,15,12,.86);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.06em;color:var(--stone);
}

/* ===== 卡片与折叠块 ===== */
.card{
  position:relative;padding:clamp(20px,2.4vw,30px);
  background:rgba(42,48,56,.55);border:1px solid var(--line-soft);
}
.card__title{font-family:var(--font-display);font-size:clamp(18px,2vw,22px);line-height:1.35;letter-spacing:-.01em}
.card__meta{margin-top:10px;font-family:var(--font-mono);font-size:12px;letter-spacing:.1em;color:var(--stone)}
.fold{border:1px solid var(--line-soft);background:rgba(58,42,32,.32)}
.fold__head{
  display:flex;align-items:center;gap:12px;width:100%;padding:16px 18px;
  text-align:left;font-size:16px;color:var(--cream);
}
.fold__head::after{content:"+";margin-left:auto;font-family:var(--font-mono);color:var(--gold)}
.fold[data-open="true"] .fold__head::after{content:"–"}
.fold__body{display:none;padding:0 18px 18px;font-size:15px;color:rgba(242,237,228,.8)}
.fold[data-open="true"] .fold__body{display:block}

/* ===== 章节目录 ===== */
.chapter-rail{
  position:sticky;top:96px;align-self:start;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--stone);
}
.chapter-rail__title{margin-bottom:14px;color:var(--gold);letter-spacing:.2em}
.chapter-rail__list li + li{margin-top:10px}
.chapter-rail__link{
  display:block;padding:2px 0 2px 14px;border-left:1px solid var(--line-soft);
  color:var(--stone);transition:color .25s ease,border-color .25s ease;
}
.chapter-rail__link:hover{color:var(--cream)}
.chapter-rail__link[data-active="true"]{color:var(--gold);border-color:var(--gold)}

/* ===== 进场显影 ===== */
[data-reveal]{opacity:0;transform:translateY(12px);transition:opacity .4s ease,transform .4s ease}
[data-reveal="in"]{opacity:1;transform:none}

/* ===== 跳转链接 ===== */
.skip-link{
  position:fixed;left:14px;top:-72px;z-index:300;
  padding:10px 18px;background:var(--gold);color:var(--ink);
  font-size:14px;letter-spacing:.06em;transition:top .2s ease;
}
.skip-link:focus{top:14px}

/* ===== 头部 ===== */
.site-header{
  position:sticky;top:0;z-index:120;
  background:var(--ink);border-bottom:1px solid var(--line);
}
.header-top{
  overflow:hidden;max-height:42px;
  background:linear-gradient(90deg,var(--walnut) 0%,rgba(14,15,12,.5) 58%,var(--ink) 100%);
  border-bottom:1px solid var(--line-soft);
  transition:max-height .3s ease,opacity .25s ease;
}
.site-header[data-compact="true"] .header-top{max-height:0;opacity:0}
.header-top__inner{
  display:flex;align-items:center;gap:clamp(12px,3vw,34px);
  min-height:42px;font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;
}
.header-top__brand{color:var(--cream);letter-spacing:.16em;white-space:nowrap}
.header-top__coord{color:var(--stone);white-space:nowrap}
.header-top__actions{margin-left:auto;display:flex;align-items:center;gap:20px;white-space:nowrap}
.header-top__icp{color:var(--stone)}
.header-top__link{
  color:var(--stone);border-bottom:1px solid transparent;
  transition:color .25s ease,border-color .25s ease;
}
.header-top__link:hover{color:var(--cream);border-color:var(--gold)}

.header-main{position:relative}
.header-main__inner{
  display:flex;align-items:center;gap:clamp(14px,2.4vw,30px);
  min-height:var(--header-h);padding-block:10px;
  transition:min-height .25s ease,padding .25s ease;
}
.site-header[data-compact="true"] .header-main__inner{min-height:56px;padding-block:6px}

.brand{display:inline-flex;align-items:center;gap:11px;flex:0 0 auto}
.brand__mark{
  width:26px;height:26px;flex:0 0 auto;
  border:1px solid var(--gold);
  background-image:conic-gradient(from 90deg,var(--gold) 0 25%,transparent 0 50%,var(--gold) 0 75%,transparent 0);
  background-size:13px 13px;
}
.brand__text{display:flex;flex-direction:column;line-height:1.15}
.brand__name{
  font-family:var(--font-display);font-size:18px;font-weight:700;
  letter-spacing:.08em;color:var(--cream);font-stretch:92%;
}
.brand__sub{font-family:var(--font-mono);font-size:10px;letter-spacing:.18em;color:var(--stone)}

.site-nav{margin-left:auto}
.site-nav__list{display:flex;align-items:center;gap:clamp(12px,1.8vw,26px)}
.site-nav__link{
  position:relative;display:inline-block;padding:6px 2px;
  font-size:15px;letter-spacing:.04em;color:var(--stone);
  transition:color .25s ease;
}
.site-nav__link::after{
  content:"";position:absolute;left:0;right:0;bottom:0;height:1px;
  background:var(--gold);transform:scaleX(0);transform-origin:left;
  transition:transform .25s ease;
}
.site-nav__link:hover{color:var(--cream)}
.site-nav__link:hover::after{transform:scaleX(1)}
.site-nav__link[aria-current="page"]{color:var(--gold)}
.site-nav__link[aria-current="page"]::after{transform:scaleX(1)}

.mini-channel{
  display:inline-flex;align-items:center;gap:8px;flex:0 0 auto;
  padding:9px 16px;border:1px solid var(--jade);
  background:rgba(47,143,131,.16);color:var(--jade-lt);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.1em;
  transition:background .25s ease,border-color .25s ease,color .25s ease;
}
.mini-channel__dot{width:6px;height:6px;background:var(--jade-lt);border-radius:50%;flex:0 0 auto}
.mini-channel:hover{background:var(--jade);border-color:var(--jade-lt);color:#06201D}
.mini-channel:hover .mini-channel__dot{background:#06201D}

.nav-toggle{
  display:none;align-items:center;gap:10px;margin-left:auto;
  padding:9px 14px;border:1px solid var(--line);color:var(--cream);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.12em;
}
.nav-toggle__bars{position:relative;display:block;width:18px;height:2px;background:currentColor}
.nav-toggle__bars::before,.nav-toggle__bars::after{
  content:"";position:absolute;left:0;width:18px;height:2px;background:currentColor;
  transition:transform .25s ease,opacity .25s ease;
}
.nav-toggle__bars::before{top:-6px}
.nav-toggle__bars::after{top:6px}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars{background:transparent}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before{transform:translateY(6px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after{transform:translateY(-6px) rotate(-45deg)}

.scroll-progress{
  position:absolute;left:0;bottom:-1px;width:100%;height:2px;z-index:2;
  background:linear-gradient(90deg,var(--jade),var(--gold) 55%,var(--cinnabar));
  transform:scaleX(0);transform-origin:left;pointer-events:none;
}

/* ===== 页脚 ===== */
.site-footer{
  position:relative;overflow:hidden;
  background:var(--walnut);color:var(--cream);
  border-top:1px solid rgba(201,162,39,.38);
}
.site-footer::before{
  content:"";position:absolute;inset:0;pointer-events:none;
  background-image:
    linear-gradient(rgba(242,237,228,.05) 1px,transparent 1px),
    linear-gradient(90deg,rgba(242,237,228,.05) 1px,transparent 1px);
  background-size:56px 56px;
}
.footer-grid{
  position:relative;display:grid;gap:clamp(24px,3vw,48px);
  grid-template-columns:1.5fr 1fr 1fr 1.7fr;
  padding-block:clamp(40px,6vw,76px);
}
.footer-brand__note{margin-top:16px;max-width:34ch;font-size:15px;line-height:1.85;color:rgba(242,237,228,.76)}
.footer-brand__coord{margin-top:14px;font-family:var(--font-mono);font-size:12px;letter-spacing:.16em;color:var(--gold)}
.footer-col__title{
  margin-bottom:16px;font-family:var(--font-mono);font-size:12px;
  font-weight:400;letter-spacing:.2em;color:var(--gold);
}
.footer-col__list li + li{margin-top:10px}
.footer-col__list a{
  font-size:15px;color:rgba(242,237,228,.78);
  transition:color .25s ease;
}
.footer-col__list a:hover{color:var(--cream)}
.footer-col--contact .footer-contact__line{
  font-size:15px;line-height:1.9;color:rgba(242,237,228,.78);
}
.footer-contact__line + .footer-contact__line{margin-top:4px}
.footer-contact__label{
  display:inline-block;min-width:5.4em;margin-right:8px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--stone);
}
.footer-legal{
  position:relative;display:flex;flex-wrap:wrap;align-items:center;gap:12px 28px;
  padding-block:20px;border-top:1px solid var(--line-cream);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.06em;color:var(--stone);
}
.footer-legal__links{display:flex;flex-wrap:wrap;gap:20px;margin-left:auto}
.footer-legal__links a{color:var(--stone);transition:color .25s ease}
.footer-legal__links a:hover{color:var(--gold)}
.footer-legal__icp{color:var(--stone)}

/* ===== 固定反馈带与返回顶部 ===== */
.feedback-bar{
  position:fixed;left:0;right:0;bottom:0;z-index:130;
  min-height:var(--bar-h);
  padding-bottom:env(safe-area-inset-bottom,0px);
  background:linear-gradient(90deg,rgba(58,42,32,.98),rgba(14,15,12,.98));
  border-top:1px solid var(--cinnabar);
}
.feedback-bar__inner{
  display:flex;align-items:center;gap:16px;
  width:100%;max-width:var(--wrap);margin-inline:auto;
  min-height:var(--bar-h);padding-inline:var(--gut);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--stone);
}
.feedback-bar__text{min-width:0}
.feedback-bar__cta{
  margin-left:auto;display:inline-flex;align-items:center;
  padding:8px 16px;background:var(--cinnabar);color:var(--cream);
  font-family:var(--font-body);font-size:13px;letter-spacing:.06em;
  transition:background .25s ease;
}
.feedback-bar__cta:hover{background:#c94a39}

.to-top{
  position:fixed;right:clamp(14px,3vw,32px);
  bottom:calc(var(--bar-h) + 14px + env(safe-area-inset-bottom,0px));
  z-index:125;display:inline-flex;align-items:center;justify-content:center;
  width:46px;height:46px;border:1px solid var(--line);
  background:rgba(42,48,56,.94);color:var(--cream);font-size:17px;
  opacity:0;visibility:hidden;transform:translateY(8px);
  transition:opacity .28s ease,transform .28s ease,visibility .28s ease,border-color .25s ease;
}
.to-top[data-visible="true"]{opacity:1;visibility:visible;transform:none}
.to-top:hover{border-color:var(--gold);color:var(--gold)}

/* ===== 响应式 ===== */
@media (max-width:1100px){
  .footer-grid{grid-template-columns:1.4fr 1fr 1fr;row-gap:36px}
  .footer-col--contact{grid-column:1 / -1;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 24px;align-content:start}
  .footer-col--contact .footer-col__title{grid-column:1 / -1}
}
@media (max-width:920px){
  :root{--header-h:62px}
  .nav-toggle{display:inline-flex}
  .site-nav{
    position:absolute;left:0;right:0;top:100%;display:none;margin:0;
    background:var(--night);border-bottom:1px solid var(--gold);
    box-shadow:0 18px 40px rgba(0,0,0,.55);
  }
  .site-nav[data-open="true"]{display:block}
  .site-nav__list{flex-direction:column;align-items:stretch;gap:0;padding:6px var(--gut) 22px}
  .site-nav__link{display:block;padding:15px 0;font-size:17px;border-bottom:1px solid var(--line-soft)}
  .site-nav__link::after{display:none}
  .site-nav__list li:last-child .site-nav__link{border-bottom:0}
  .site-nav__link[aria-current="page"]{color:var(--gold);border-bottom-color:rgba(201,162,39,.45)}
  .mini-channel{margin-left:0}
  .grid--5-7,.grid--4-8,.grid--3{grid-template-columns:minmax(0,1fr)}
  .chapter-rail{position:static;top:auto;margin-bottom:24px}
}
@media (max-width:760px){
  body{font-size:16px}
  .header-top__coord,.header-top__icp{display:none}
  .header-top__actions{margin-left:auto}
  .grid--2{grid-template-columns:minmax(0,1fr)}
  .footer-grid{grid-template-columns:minmax(0,1fr);row-gap:32px}
  .footer-col--contact{grid-template-columns:minmax(0,1fr)}
  .footer-legal__links{margin-left:0}
}
@media (max-width:560px){
  .brand__sub{display:none}
  .mini-channel{padding:8px 12px;font-size:11px;letter-spacing:.06em}
  .mini-channel__dot{width:5px;height:5px}
  .feedback-bar__text{display:none}
  .feedback-bar__cta{margin-left:0}
  .to-top{right:14px;width:42px;height:42px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.01ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.01ms !important;
  }
  [data-reveal]{opacity:1;transform:none}
}