/* ==========================================================================
   启博EPN · /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 页头 / 页脚 / 通用组件 / 网格 / 响应式
   ========================================================================== */

/* ---------- 1. Tokens ---------- */
:root{
  --ink-black:#05070C;
  --midnight:#0B1220;
  --deep-sea:#12203A;
  --tech-blue:#1F5BFF;
  --electric:#00E5D0;
  --electric-soft:#8CF6EC;
  --coral:#FF6B3D;
  --amber:#FFC24B;
  --paper:#F6F8FB;
  --ink:#101418;
  --graphite:#7A8598;
  --line:#D7DEE8;
  --line-dark:rgba(215,222,232,.14);
  --line-dark-strong:rgba(215,222,232,.3);

  --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","IBM Plex Mono","SFMono-Regular",Consolas,"Liberation Mono",Menlo,monospace;

  --header-h:78px;
  --shell:1240px;
  --gutter:clamp(20px,5vw,56px);
  --cut:16px;
  --ease:cubic-bezier(.22,.61,.36,1);
}

/* ---------- 2. Reset ---------- */
*,*::before,*::after{box-sizing:border-box;}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;}
body{
  margin:0;
  padding-top:var(--header-h);
  background:var(--ink-black);
  color:var(--paper);
  font-family:var(--font-sans);
  font-size:16px;
  line-height:1.75;
  font-weight:400;
  overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
body,p,ul,ol,dl,figure,blockquote,h1,h2,h3,h4,h5,h6{margin:0;}
ul,ol{padding:0;}
img,svg,video{max-width:100%;display:block;height:auto;}
table{border-collapse:collapse;}
hr{border:0;height:1px;background:var(--line-dark);margin:0;}
a{color:var(--electric);text-decoration:none;transition:color .2s var(--ease);}
a:hover{color:var(--electric-soft);}
button{font:inherit;color:inherit;}
::selection{background:var(--electric);color:#04201D;}
:focus-visible{outline:2px solid var(--electric);outline-offset:2px;border-radius:2px;}
:focus:not(:focus-visible){outline:none;}

/* ---------- 3. 中文排版层级 ---------- */
h1,.h1{font-size:clamp(2rem,3.6vw,3rem);line-height:1.15;font-weight:900;letter-spacing:-.01em;}
h2,.h2{font-size:clamp(1.6rem,3vw,2.4rem);line-height:1.15;font-weight:900;letter-spacing:-.01em;margin:0 0 .5em;}
h3,.h3{font-size:clamp(1.15rem,1.6vw,1.35rem);line-height:1.3;font-weight:800;margin:0 0 .5em;}
h4,.h4{font-size:1.05rem;line-height:1.4;font-weight:700;margin:0 0 .4em;}
.display{font-size:clamp(2.6rem,6vw,5rem);line-height:1.05;font-weight:900;letter-spacing:-.01em;}
.mono{font-family:var(--font-mono);letter-spacing:.02em;}
.meta-mono{font-family:var(--font-mono);font-size:12.5px;letter-spacing:.04em;color:var(--graphite);}
.idx{font-family:var(--font-mono);font-size:13px;letter-spacing:.08em;color:var(--electric);}
.eyebrow{display:inline-block;font-family:var(--font-mono);font-size:12.5px;letter-spacing:.18em;text-transform:uppercase;color:var(--graphite);}

.prose{font-size:16.5px;line-height:1.75;color:rgba(246,248,251,.82);max-width:44em;}
.prose p{margin:0 0 1.1em;}
.prose h2,.prose h3,.prose h4{color:var(--paper);margin-top:1.6em;}
.prose ul,.prose ol{margin:0 0 1.1em;padding-left:1.3em;}
.prose li{margin:.35em 0;}
.prose strong{color:var(--paper);font-weight:700;}
.prose code{font-family:var(--font-mono);font-size:.9em;color:var(--electric);background:rgba(0,229,208,.08);padding:2px 6px;}
.panel--paper .prose,.paper-section .prose{color:#2A3444;}
.panel--paper .prose h2,.panel--paper .prose h3,.paper-section .prose h2,.paper-section .prose h3{color:var(--ink);}
.panel--paper a,.paper-section a{color:var(--tech-blue);}

/* ---------- 4. 布局工具 ---------- */
.shell{width:100%;max-width:var(--shell);margin:0 auto;padding:0 var(--gutter);}
.shell--narrow{max-width:820px;}
.grid-12{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:clamp(16px,2.4vw,28px);}
.g-3{grid-column:span 3;}
.g-4{grid-column:span 4;}
.g-5{grid-column:span 5;}
.g-6{grid-column:span 6;}
.g-7{grid-column:span 7;}
.g-8{grid-column:span 8;}
.g-9{grid-column:span 9;}
.g-12{grid-column:span 12;}
.stack{display:flex;flex-direction:column;gap:var(--gap,24px);}
.cluster{display:flex;flex-wrap:wrap;gap:12px;align-items:center;}
.stripe-divider{
  height:1px;width:100%;border:0;
  background:repeating-linear-gradient(90deg,var(--line-dark-strong) 0 2px,transparent 2px 10px);
  margin:clamp(32px,4.4vw,60px) 0;
}
.corner-frame{position:relative;}
.corner-frame::before,.corner-frame::after{content:"";position:absolute;inset:10px;pointer-events:none;opacity:.5;}
.corner-frame::before{
  background:
    linear-gradient(var(--electric-soft),var(--electric-soft)) 0 0/16px 1px no-repeat,
    linear-gradient(var(--electric-soft),var(--electric-soft)) 0 0/1px 16px no-repeat,
    linear-gradient(var(--electric-soft),var(--electric-soft)) 100% 0/16px 1px no-repeat,
    linear-gradient(var(--electric-soft),var(--electric-soft)) 100% 0/1px 16px no-repeat;
}
.corner-frame::after{
  background:
    linear-gradient(var(--electric-soft),var(--electric-soft)) 0 100%/16px 1px no-repeat,
    linear-gradient(var(--electric-soft),var(--electric-soft)) 0 100%/1px 16px no-repeat,
    linear-gradient(var(--electric-soft),var(--electric-soft)) 100% 100%/16px 1px no-repeat,
    linear-gradient(var(--electric-soft),var(--electric-soft)) 100% 100%/1px 16px no-repeat;
}

/* ---------- 5. Skip link ---------- */
.skip-link{
  position:fixed;top:10px;left:10px;z-index:200;
  transform:translateY(-200%);
  background:var(--electric);color:#04201D;
  font-size:14px;font-weight:700;letter-spacing:.02em;
  padding:11px 18px;text-decoration:none;
  transition:transform .2s var(--ease);
}
.skip-link:focus{transform:translateY(0);color:#04201D;}

/* ---------- 6. 按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  min-height:44px;padding:0 18px;
  font-size:14.5px;font-weight:600;letter-spacing:.01em;line-height:1;
  border:1px solid transparent;border-radius:2px;
  background:transparent;color:var(--paper);cursor:pointer;
  text-decoration:none;white-space:nowrap;
  transition:background .22s var(--ease),color .22s var(--ease),border-color .22s var(--ease),transform .22s var(--ease);
}
.btn:active{transform:translateY(1px);}
.btn-accent{background:var(--coral);color:#1A0703;}
.btn-accent:hover{background:#FF855E;color:#1A0703;}
.btn-electric{background:var(--electric);color:#04201D;}
.btn-electric:hover{background:var(--electric-soft);color:#04201D;}
.btn-ghost{border-color:var(--line-dark-strong);color:var(--paper);}
.btn-ghost:hover{border-color:var(--electric);color:var(--electric);}

/* ---------- 7. 页头 ---------- */
.site-header{
  position:fixed;top:0;left:0;right:0;z-index:90;
  height:var(--header-h);
  background:linear-gradient(180deg,rgba(5,7,12,.94) 0%,rgba(5,7,12,.74) 64%,rgba(5,7,12,0) 100%);
  border-bottom:1px solid transparent;
  transition:background .3s var(--ease),border-color .3s var(--ease),box-shadow .3s var(--ease);
}
.site-header[data-scrolled="true"]{
  background:var(--midnight);
  border-bottom-color:var(--line-dark);
  box-shadow:0 20px 44px -34px rgba(0,0,0,.95);
}
.header-inner{
  position:relative;z-index:2;
  max-width:var(--shell);height:100%;margin:0 auto;
  padding:0 var(--gutter);
  display:flex;align-items:center;gap:clamp(12px,2vw,30px);
}
.brand{display:flex;align-items:center;gap:clamp(10px,1.4vw,18px);min-width:0;flex:0 0 auto;}
.brand-code{
  font-size:11.5px;letter-spacing:.16em;color:var(--electric);
  padding:5px 9px;border:1px solid rgba(0,229,208,.35);
  background:rgba(0,229,208,.07);
}
.brand-mark{display:flex;flex-direction:column;gap:5px;text-decoration:none;color:var(--paper);}
.brand-mark:hover{color:var(--paper);}
.brand-name{font-size:19px;font-weight:900;letter-spacing:-.01em;line-height:1.1;position:relative;padding-bottom:6px;}
.brand-name::after{
  content:"";position:absolute;left:0;bottom:0;width:34px;height:2px;
  background:linear-gradient(90deg,var(--electric),rgba(0,229,208,0));
}
.brand-sub{font-size:10.5px;letter-spacing:.14em;color:var(--graphite);line-height:1;}

.primary-nav{margin-left:auto;}
.primary-nav ul{display:flex;align-items:center;gap:2px;list-style:none;margin:0;padding:0;}
.primary-nav a{
  position:relative;
  display:flex;align-items:center;height:44px;padding:0 12px;
  font-size:14.5px;font-weight:500;color:rgba(246,248,251,.76);
  text-decoration:none;white-space:nowrap;border-radius:2px;
  transition:color .2s var(--ease),background .2s var(--ease);
}
.primary-nav a::after{
  content:"";position:absolute;left:12px;right:12px;bottom:8px;height:1px;
  background:var(--electric);transform:scaleX(0);transform-origin:left center;
  transition:transform .28s var(--ease);
}
.primary-nav a:hover{color:var(--paper);}
.primary-nav a:hover::after{transform:scaleX(1);}
.primary-nav a[aria-current="page"]{color:var(--paper);background:rgba(0,229,208,.09);}
.primary-nav a[aria-current="page"]::after{transform:scaleX(1);}

.header-actions{display:flex;align-items:center;gap:12px;flex:0 0 auto;}
.week-chip{
  display:inline-flex;align-items:center;gap:7px;
  font-size:12px;letter-spacing:.08em;color:var(--amber);
  padding:5px 10px;border:1px solid rgba(255,194,75,.36);background:rgba(255,194,75,.08);
}
.week-chip .dot{width:6px;height:6px;border-radius:50%;background:var(--amber);}

.nav-toggle{
  display:none;position:relative;width:44px;height:44px;padding:0;
  align-items:center;justify-content:center;
  background:transparent;border:1px solid var(--line-dark-strong);border-radius:2px;
  cursor:pointer;transition:border-color .2s var(--ease);
}
.nav-toggle:hover{border-color:var(--electric);}
.nav-toggle-lines{display:block;width:18px;height:12px;position:relative;}
.nav-toggle-lines i{position:absolute;left:0;width:100%;height:1.5px;background:currentColor;transition:transform .25s var(--ease),opacity .2s var(--ease);}
.nav-toggle-lines i:nth-child(1){top:0;}
.nav-toggle-lines i:nth-child(2){top:5px;}
.nav-toggle-lines i:nth-child(3){top:10px;}
.nav-toggle[aria-expanded="true"] .nav-toggle-lines i:nth-child(1){transform:translateY(5px) rotate(45deg);}
.nav-toggle[aria-expanded="true"] .nav-toggle-lines i:nth-child(2){opacity:0;}
.nav-toggle[aria-expanded="true"] .nav-toggle-lines i:nth-child(3){transform:translateY(-5px) rotate(-45deg);}

.scroll-progress{
  position:absolute;left:0;right:0;bottom:-1px;height:2px;
  transform:scaleX(0);transform-origin:left center;
  background:linear-gradient(90deg,var(--tech-blue),var(--electric) 58%,var(--amber));
  transition:transform .12s linear;
}
html.nav-open{overflow:hidden;}

/* ---------- 8. 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:clamp(64px,8vw,120px);
  background:var(--ink-black);
  border-top:1px solid var(--line-dark);
  padding:clamp(44px,5vw,72px) var(--gutter) 0;
}
.footer-inner{
  max-width:var(--shell);margin:0 auto;
  display:grid;grid-template-columns:minmax(0,5fr) minmax(0,7fr);
  gap:clamp(32px,5vw,72px);
  padding-bottom:clamp(32px,4vw,56px);
}
.footer-mark{display:inline-block;font-size:22px;font-weight:900;letter-spacing:-.01em;color:var(--paper);text-decoration:none;}
.footer-mark:hover{color:var(--paper);}
.footer-mark::after{content:"";display:block;width:46px;height:2px;margin-top:9px;background:linear-gradient(90deg,var(--electric),rgba(0,229,208,0));}
.footer-tag{margin-top:16px;font-size:11px;letter-spacing:.16em;color:var(--graphite);text-transform:uppercase;}
.footer-contact{margin-top:18px;font-size:13px;line-height:1.95;color:rgba(246,248,251,.72);}
.footer-note{margin-top:14px;font-size:14px;line-height:1.75;color:var(--graphite);max-width:32em;}
.footer-cols{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:clamp(20px,3vw,32px);}
.footer-col-title{font-size:11.5px;letter-spacing:.16em;text-transform:uppercase;color:var(--electric);font-weight:500;margin-bottom:14px;}
.footer-col ul{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:2px;}
.footer-col a{
  display:inline-flex;align-items:center;min-height:40px;
  font-size:14.5px;color:rgba(246,248,251,.7);text-decoration:none;
  transition:color .2s var(--ease),padding-left .2s var(--ease);
}
.footer-col a:hover{color:var(--electric);padding-left:6px;}
.footer-base{
  max-width:var(--shell);margin:0 auto;
  border-top:1px solid var(--line-dark);
  padding:16px 0 30px;
  display:flex;flex-wrap:wrap;align-items:center;gap:10px 26px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.02em;color:var(--graphite);
}
.to-top{
  display:inline-flex;align-items:center;gap:10px;margin-left:auto;
  min-height:44px;padding:0 4px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.06em;
  color:var(--graphite);text-decoration:none;
}
.to-top::before{
  content:"";width:1px;height:22px;background:var(--electric);
  animation:rail-pulse 2.4s var(--ease) infinite;
}
.to-top:hover{color:var(--electric);}
@keyframes rail-pulse{
  0%,100%{opacity:.35;transform:scaleY(.62);}
  50%{opacity:1;transform:scaleY(1);}
}

/* ---------- 9. 面包屑 / 章节标签 ---------- */
.breadcrumb{padding:20px 0 8px;font-family:var(--font-mono);font-size:12px;letter-spacing:.04em;color:var(--graphite);}
.breadcrumb ol{display:flex;flex-wrap:wrap;gap:8px;list-style:none;margin:0;padding:0;}
.breadcrumb li{display:flex;align-items:center;gap:8px;}
.breadcrumb li + li::before{content:"/";color:rgba(0,229,208,.55);}
.breadcrumb a{color:var(--graphite);text-decoration:none;}
.breadcrumb a:hover{color:var(--electric);}
.breadcrumb [aria-current="page"]{color:var(--paper);}
.section-label{
  display:flex;align-items:center;gap:14px;margin-bottom:18px;
  font-family:var(--font-mono);font-size:12.5px;letter-spacing:.18em;text-transform:uppercase;color:var(--electric);
}
.section-label::after{content:"";height:1px;flex:1;background:linear-gradient(90deg,rgba(0,229,208,.55),rgba(0,229,208,0));}

/* ---------- 10. 面板 / 标签 / 卡片 ---------- */
.panel{
  position:relative;background:var(--midnight);
  border:1px solid var(--line-dark);
  padding:clamp(22px,3vw,40px);
}
.panel--sea{background:var(--deep-sea);}
.panel--cut{clip-path:polygon(var(--cut) 0,100% 0,100% calc(100% - var(--cut)),calc(100% - var(--cut)) 100%,0 100%,0 var(--cut));}
.panel--paper{background:var(--paper);color:var(--ink);border-color:var(--line);}
.panel--paper .section-label{color:var(--tech-blue);}
.panel--paper .meta-mono,.panel--paper .eyebrow{color:#5C6879;}
.panel--paper .idx{color:var(--tech-blue);}
.panel-title{font-size:clamp(1.05rem,1.5vw,1.3rem);font-weight:800;line-height:1.3;letter-spacing:-.005em;margin-bottom:.5em;}

.tag{
  display:inline-flex;align-items:center;gap:6px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.06em;
  padding:4px 9px;border:1px solid var(--line-dark-strong);
  color:rgba(246,248,251,.8);background:rgba(255,255,255,.02);
}
.tag--amber{color:var(--amber);border-color:rgba(255,194,75,.4);background:rgba(255,194,75,.08);}
.tag--electric{color:var(--electric);border-color:rgba(0,229,208,.42);background:rgba(0,229,208,.08);}
.tag--coral{color:var(--coral);border-color:rgba(255,107,61,.45);background:rgba(255,107,61,.09);}
.panel--paper .tag{color:#3A4553;border-color:var(--line);background:rgba(16,20,24,.03);}
.panel--paper .tag--electric{color:#007C71;border-color:rgba(0,160,146,.4);background:rgba(0,229,208,.14);}

/* ---------- 11. 双轴结构 ---------- */
.axis-layout{
  display:grid;grid-template-columns:220px minmax(0,1fr);
  gap:clamp(32px,5vw,80px);align-items:start;
}
.index-rail{
  position:sticky;top:calc(var(--header-h) + 28px);
  display:flex;flex-direction:column;gap:2px;
  border-left:1px solid var(--line-dark);padding-left:2px;
}
.index-rail-title{
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.2em;
  color:var(--graphite);padding:0 0 10px 16px;
}
.index-link{
  position:relative;display:flex;align-items:center;
  min-height:44px;padding:0 10px 0 16px;
  font-family:var(--font-mono);font-size:13px;letter-spacing:.04em;
  color:var(--graphite);background:transparent;border:0;cursor:pointer;text-align:left;
  transition:color .2s var(--ease);
}
.index-link::before{
  content:"";position:absolute;left:0;top:50%;transform:translateY(-50%);
  width:2px;height:0;background:var(--electric);
  transition:height .26s var(--ease),box-shadow .26s var(--ease);
}
.index-link:hover{color:var(--paper);}
.index-link[data-active="true"]{color:var(--electric);}
.index-link[data-active="true"]::before{height:62%;box-shadow:0 0 10px rgba(0,229,208,.7);}
.axis-main{min-width:0;}

/* ---------- 12. 图片容器（供页面阶段放置占位图） ---------- */
.figure{
  position:relative;display:block;margin:0;overflow:hidden;
  background:var(--midnight);border:1px solid var(--line-dark);
}
.figure::before{
  content:"";position:absolute;inset:0;pointer-events:none;z-index:0;
  background-image:
    linear-gradient(rgba(0,229,208,.07) 1px,transparent 1px),
    linear-gradient(90deg,rgba(0,229,208,.07) 1px,transparent 1px);
  background-size:34px 34px;
}
.figure img{position:relative;z-index:1;width:100%;height:100%;object-fit:cover;aspect-ratio:16/9;}
.figure--wide img{aspect-ratio:21/9;}
.figure--tall img{aspect-ratio:4/5;}
.figure--square img{aspect-ratio:1/1;}
.figure figcaption{
  position:relative;z-index:1;padding:10px 13px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.03em;
  color:var(--graphite);border-top:1px solid var(--line-dark);background:var(--midnight);
}
.figure-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:clamp(12px,1.8vw,20px);}
.panel--paper .figure{background:#E9EEF5;border-color:var(--line);}
.panel--paper .figure figcaption{background:#E9EEF5;border-top-color:var(--line);color:#5C6879;}

/* ---------- 13. 动效 / 滚动显现 ---------- */
html.js [data-reveal]{
  opacity:0;transform:translateY(18px);
  transition:opacity .45s var(--ease),transform .45s var(--ease);
  transition-delay:var(--reveal-delay,0ms);
  will-change:opacity,transform;
}
html.js [data-reveal].is-in{opacity:1;transform:none;}

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

/* ---------- 14. 响应式 ---------- */
@media (max-width:1180px){
  .brand-sub{display:none;}
}
@media (max-width:1080px){
  .brand-code{display:none;}
}
@media (max-width:1000px){
  :root{--header-h:68px;}
  .nav-toggle{display:inline-flex;}
  .primary-nav{
    position:fixed;top:var(--header-h);left:0;right:0;
    margin-left:0;display:none;
    max-height:calc(100dvh - var(--header-h));
    overflow-y:auto;
    background:var(--midnight);
    border-top:1px solid var(--line-dark);
    border-bottom:1px solid var(--line-dark);
    box-shadow:0 44px 70px -40px rgba(0,0,0,.95);
    padding:8px var(--gutter) 26px;
  }
  .primary-nav[data-open]{display:block;}
  .primary-nav ul{flex-direction:column;align-items:stretch;gap:0;}
  .primary-nav li + li{border-top:1px solid var(--line-dark);}
  .primary-nav a{width:100%;height:54px;padding:0;font-size:17px;border-radius:0;}
  .primary-nav a::after{left:0;right:auto;width:36px;bottom:13px;}
  .axis-layout{grid-template-columns:minmax(0,1fr);gap:28px;}
  .index-rail{
    position:static;flex-direction:row;flex-wrap:wrap;gap:0 4px;
    border-left:0;border-top:1px solid var(--line-dark);
    border-bottom:1px solid var(--line-dark);padding:6px 0;
  }
  .index-rail-title{display:none;}
  .index-link{padding:0 12px;min-height:42px;}
  .index-link::before{left:6px;right:6px;top:auto;bottom:0;width:auto;height:2px;transform:none;}
  .index-link[data-active="true"]::before{height:2px;width:auto;}
}
@media (max-width:900px){
  .g-3,.g-4,.g-5,.g-6,.g-7,.g-8,.g-9{grid-column:span 12;}
  .footer-inner{grid-template-columns:minmax(0,1fr);}
  .footer-cols{grid-template-columns:repeat(2,minmax(0,1fr));gap:24px 20px;}
}
@media (max-width:640px){
  .header-actions{gap:8px;}
  .week-chip{display:none;}
  .btn{padding:0 14px;font-size:14px;}
  .footer-cols{grid-template-columns:minmax(0,1fr);}
  .footer-base{font-size:11px;gap:8px 16px;}
  .to-top{margin-left:0;}
}
@media (max-width:420px){
  .btn-accent{padding:0 12px;font-size:13.5px;}
}