/* ================= 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,blockquote,dl,dd,address{margin:0}
ul,ol{list-style:none;padding:0}
img,svg,video{display:block;max-width:100%}
button{font:inherit;color:inherit;background:none;border:0;padding:0;cursor:pointer}
a{color:inherit;text-decoration:none}
:where(h1,h2,h3,h4){font-weight:900;line-height:1.1;letter-spacing:-.01em}

/* ================= tokens ================= */
:root{
  --ink:#0B1B2B;
  --panel:#13293D;
  --night:#07131F;
  --paper:#F7F4EC;
  --lemon:#F2D64B;
  --coral:#FF6B4A;
  --cyan:#3FE0C5;
  --mist:#8FA3B0;
  --line:#2B4257;
  --text:#DCE6ED;
  --text-dim:#A7BAC6;
  --font-sans:"Source Han Sans SC","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-mono:"IBM Plex Mono","JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,"Courier New",monospace;
  --font-hand:"LXGW WenKai","霞鹜文楷","Kaiti SC","STKaiti","Songti SC",serif;
  --shell-max:1220px;
  --gutter:clamp(16px,4vw,40px);
  --baseline:24px;
  --radius:3px;
  --ease:cubic-bezier(.22,.61,.36,1);
  --header-shadow:0 26px 44px -34px rgba(0,0,0,.95);
}

/* ================= base ================= */
body{
  min-height:100vh;
  background:var(--ink);
  color:var(--text);
  font-family:var(--font-sans);
  font-size:16px;
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
:focus-visible{outline:2px solid var(--lemon);outline-offset:3px;border-radius:2px}
::selection{background:var(--lemon);color:var(--night)}
#main-content{scroll-margin-top:112px}
#main-content:focus{outline:none}

/* ================= utilities ================= */
.shell{width:100%;max-width:var(--shell-max);margin-inline:auto;padding-inline:var(--gutter)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums;letter-spacing:.04em}
.hand{font-family:var(--font-hand);font-style:normal}

/* skip link */
.skip-link{
  position:fixed;top:10px;left:12px;z-index:200;
  transform:translateY(-180%);
  background:var(--lemon);color:var(--night);
  font-size:14px;font-weight:700;padding:10px 16px;border-radius:2px;
  box-shadow:0 6px 18px -8px rgba(0,0,0,.8);
  transition:transform .18s var(--ease);
}
.skip-link:focus,.skip-link:focus-visible{transform:translateY(0)}

/* ================= header ================= */
.site-header{
  position:sticky;top:0;z-index:80;
  background:var(--night);
  border-bottom:1px solid var(--line);
  box-shadow:var(--header-shadow);
}
.header-rail{
  background:linear-gradient(90deg,rgba(63,224,197,.12),rgba(242,214,75,.06) 46%,rgba(7,19,31,0) 80%);
  border-bottom:1px solid rgba(43,66,87,.9);
}
.header-rail__inner{
  display:flex;align-items:center;gap:14px;
  min-height:34px;font-size:12px;color:var(--text-dim);
  white-space:nowrap;overflow:hidden;
}
.rail-dot{
  flex:0 0 auto;width:7px;height:7px;border-radius:50%;
  background:var(--cyan);box-shadow:0 0 0 3px rgba(63,224,197,.16);
  animation:rail-breath 3.8s ease-in-out infinite;
}
@keyframes rail-breath{
  0%,100%{opacity:.5;box-shadow:0 0 0 2px rgba(63,224,197,.12)}
  50%{opacity:1;box-shadow:0 0 0 6px rgba(63,224,197,.05)}
}
.rail-label{font-size:11px;color:var(--lemon)}
.rail-sep{width:1px;height:12px;background:var(--line);flex:0 0 auto}
.rail-text{min-width:0;overflow:hidden;text-overflow:ellipsis}
.rail-note{
  margin-left:auto;flex:0 0 auto;
  font-size:11px;color:var(--cyan);
  border-bottom:1px solid rgba(63,224,197,.45);padding-bottom:1px;
  transition:color .16s var(--ease),border-color .16s var(--ease);
}
.rail-note:hover{color:var(--lemon);border-bottom-color:var(--lemon)}

.command-bar{position:relative;background:var(--ink)}
.command-bar__inner{
  display:flex;align-items:center;gap:clamp(10px,2vw,26px);
  min-height:70px;padding-block:10px;
  transition:min-height .24s var(--ease);
}
.site-header[data-scrolled="true"] .command-bar__inner{min-height:56px}

/* brand */
.brand{display:inline-flex;align-items:center;gap:11px;flex:0 0 auto}
.brand__mark{
  display:inline-grid;place-items:center;min-width:44px;padding:6px 8px;
  background:var(--lemon);color:var(--night);
  font-size:14px;font-weight:700;line-height:1;border-radius:2px;
  box-shadow:3px 3px 0 -1px rgba(255,107,74,.9);
  transition:transform .18s var(--ease),box-shadow .18s var(--ease);
}
.brand:hover .brand__mark{transform:translate(-1px,-1px);box-shadow:4px 4px 0 -1px var(--coral)}
.brand__name{display:block;font-size:17px;font-weight:900;line-height:1.2;color:var(--paper)}
.brand__desc{display:block;font-size:11px;line-height:1.4;letter-spacing:.06em;color:var(--mist)}

/* nav */
.primary-nav{display:flex;flex:1 1 auto;align-items:center;justify-content:center;gap:2px}
.nav-link{
  position:relative;display:inline-flex;align-items:baseline;gap:6px;
  padding:9px 11px;border-radius:2px;
  font-size:14px;color:#BFD0DA;
  transition:color .16s var(--ease),background-color .16s var(--ease);
}
.nav-link__index{font-size:10px;color:#5E7A8E;transition:color .16s var(--ease)}
.nav-link:hover{color:var(--lemon);background:rgba(242,214,75,.09)}
.nav-link:hover .nav-link__index{color:var(--lemon)}
.nav-link[aria-current="page"]{background:var(--lemon);color:var(--night);font-weight:700}
.nav-link[aria-current="page"] .nav-link__index{color:rgba(7,19,31,.55)}

/* actions + buttons */
.command-bar__actions{display:flex;flex:0 0 auto;align-items:center;gap:8px;margin-left:auto}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:10px 16px;border:1px solid transparent;border-radius:2px;
  font-size:13px;font-weight:700;line-height:1;letter-spacing:.02em;
  transition:background-color .16s var(--ease),color .16s var(--ease),
             border-color .16s var(--ease),transform .16s var(--ease),box-shadow .16s var(--ease);
}
.btn--primary{background:var(--coral);color:#1B0903;box-shadow:0 2px 0 rgba(0,0,0,.45)}
.btn--primary:hover{background:#FF8464;transform:translateY(-1px)}
.btn--ghost{background:transparent;border-color:var(--line);color:var(--cyan)}
.btn--ghost:hover{border-color:var(--cyan);background:rgba(63,224,197,.08)}
.btn--lemon{background:var(--lemon);color:var(--night)}
.btn--lemon:hover{background:#F8E070;transform:translateY(-1px)}
.btn--small{padding:7px 11px;font-size:12px}

/* toggle */
.nav-toggle{
  display:none;align-items:center;gap:8px;
  padding:8px 12px;border:1px solid var(--line);border-radius:2px;
  font-size:13px;font-weight:700;color:var(--text);
  transition:background-color .16s var(--ease),color .16s var(--ease),border-color .16s var(--ease);
}
.nav-toggle:hover{border-color:var(--lemon);color:var(--lemon)}
.nav-toggle[aria-expanded="true"]{background:var(--lemon);color:var(--night);border-color:var(--lemon)}
.nav-toggle__bars{display:inline-flex;flex-direction:column;gap:4px;width:16px}
.nav-toggle__bar{display:block;height:2px;width:100%;background:currentColor;transition:transform .2s var(--ease)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:first-child{transform:translateY(3px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:last-child{transform:translateY(-3px) rotate(-45deg)}
.nav-toggle__text{line-height:1}

/* reading progress */
.scroll-progress{position:absolute;left:0;right:0;bottom:-1px;height:2px;overflow:hidden;pointer-events:none}
.scroll-progress__bar{
  display:block;width:100%;height:100%;
  transform:scaleX(0);transform-origin:0 50%;
  background:linear-gradient(90deg,var(--cyan),var(--lemon) 62%,var(--coral));
  transition:transform .12s linear;
}

/* ================= footer ================= */
.site-footer{
  margin-top:clamp(40px,7vw,88px);
  background:var(--night);
  border-top:1px solid var(--line);
  color:var(--text-dim);
  font-size:14px;
  padding-top:clamp(34px,6vw,60px);
}
.footer-grid{
  display:grid;grid-template-columns:1.5fr 1fr 1fr 1.2fr;
  gap:clamp(24px,4vw,48px);
  padding-bottom:clamp(26px,4vw,46px);
}
.footer-brand{display:flex;flex-direction:column;gap:16px}
.brand--footer .brand__name{font-size:16px}
.footer-summary{max-width:34ch;font-size:13px;line-height:1.7;color:var(--text-dim)}
.status-list{display:grid;gap:9px;font-size:12px}
.status-list__item{display:flex;align-items:center;gap:9px;color:#B7C7D2}
.status-dot{flex:0 0 auto;width:7px;height:7px;border-radius:50%;background:var(--mist)}
.status-dot--cyan{background:var(--cyan);box-shadow:0 0 0 3px rgba(63,224,197,.14)}
.status-dot--lemon{background:var(--lemon);box-shadow:0 0 0 3px rgba(242,214,75,.14)}
.status-dot--coral{background:var(--coral);box-shadow:0 0 0 3px rgba(255,107,74,.14)}
.footer-col__title{
  margin-bottom:14px;padding-bottom:10px;
  border-bottom:1px solid var(--line);
  font-size:11px;font-weight:700;letter-spacing:.16em;text-transform:uppercase;color:var(--lemon);
}
.footer-links{display:grid;gap:9px}
.footer-links a{
  font-size:13.5px;color:#C3D2DC;border-bottom:1px solid transparent;
  transition:color .16s var(--ease),border-color .16s var(--ease);
}
.footer-links a:hover{color:var(--lemon);border-bottom-color:rgba(242,214,75,.5)}
.footer-address{display:grid;gap:8px;font-style:normal;font-size:12.5px;line-height:1.6;color:#B7C7D2}
.footer-contact__line{word-break:break-all}
.footer-contact__line--muted{font-size:11.5px;color:var(--mist);word-break:normal}
.footer-base{
  display:flex;flex-wrap:wrap;align-items:center;gap:12px 22px;
  padding-block:18px 24px;
  border-top:1px solid var(--line);
  font-size:12px;color:#7B93A3;
}
.footer-legal{margin-right:auto}
.footer-icp{color:var(--mist)}
.footer-legal-links{display:flex;flex-wrap:wrap;gap:16px;margin-left:auto}
.footer-legal-links a{border-bottom:1px solid transparent}
.footer-legal-links a:hover{color:var(--lemon);border-bottom-color:rgba(242,214,75,.5)}

/* ================= shared page components ================= */
.page-main{display:block}
.breadcrumbs{padding-block:18px;font-size:12px;color:var(--mist)}
.breadcrumbs ol{display:flex;flex-wrap:wrap;align-items:center;gap:8px}
.breadcrumbs li+li::before{content:"/";margin-right:8px;font-family:var(--font-mono);color:var(--line)}
.breadcrumbs a:hover{color:var(--lemon)}
.breadcrumbs [aria-current="page"]{color:var(--paper)}

.section{padding-block:clamp(30px,5.5vw,62px)}
.section__head{
  display:flex;flex-wrap:wrap;align-items:baseline;gap:10px 20px;
  margin-bottom:clamp(18px,3vw,28px);padding-bottom:14px;
  border-bottom:1px solid var(--line);
}
.eyebrow{font-family:var(--font-mono);font-size:11px;letter-spacing:.18em;text-transform:uppercase;color:var(--cyan)}
.display-title{font-size:clamp(32px,5vw,64px);line-height:1.05;color:var(--paper)}
.lede{max-width:62ch;font-size:clamp(15px,1.6vw,18px);line-height:1.7;color:#BCCBD6}

.grid{display:grid;gap:var(--baseline)}
.grid--auto{grid-template-columns:repeat(auto-fit,minmax(240px,1fr))}
.card{
  padding:clamp(16px,2.4vw,26px);
  background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
}
.card--paper{background:var(--paper);color:#16232E;border-color:#DCD4C2}
.card--paper a{color:#0B4B63}

.tag{
  display:inline-flex;align-items:center;gap:6px;
  padding:4px 9px;border-radius:2px;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.08em;
  background:var(--lemon);color:var(--night);
}
.tag--cyan{background:rgba(63,224,197,.14);color:var(--cyan);border:1px solid rgba(63,224,197,.42)}
.tag--coral{background:rgba(255,107,74,.14);color:#FF9C85;border:1px solid rgba(255,107,74,.42)}
.hand-note{font-family:var(--font-hand);font-size:13px;color:var(--lemon);transform:rotate(-1.5deg)}
.divider-rail{height:1px;margin-block:var(--baseline);background:repeating-linear-gradient(90deg,var(--line) 0 14px,transparent 14px 24px)}

.prose{max-width:68ch;font-size:15.5px;line-height:1.8;color:#C7D4DE}
.prose h2{margin-block:1.6em .6em;font-size:clamp(20px,2.4vw,26px);color:var(--paper)}
.prose h3{margin-block:1.4em .5em;font-size:17px;color:var(--paper)}
.prose p+p{margin-top:.9em}
.prose ul{display:grid;gap:.5em;margin-block:.9em}
.prose ul li{position:relative;padding-left:18px}
.prose ul li::before{content:"";position:absolute;left:0;top:.72em;width:7px;height:7px;border-radius:1px;background:var(--cyan)}
.prose a{color:var(--lemon);border-bottom:1px solid rgba(242,214,75,.45)}

.link-arrow{display:inline-flex;align-items:center;gap:7px;font-size:13.5px;font-weight:700;color:var(--cyan)}
.link-arrow::after{content:"→";transition:transform .16s var(--ease)}
.link-arrow:hover::after{transform:translateX(3px)}

/* image containers (page stage) */
.media-frame{
  position:relative;overflow:hidden;
  aspect-ratio:16/10;
  background:var(--panel);
  border:1px solid var(--line);border-radius:var(--radius);
}
.media-frame img{width:100%;height:100%;object-fit:cover}
.media-frame--wide{aspect-ratio:21/9}
.media-frame--device{aspect-ratio:9/16;max-width:320px;margin-inline:auto}
.media-frame__tag{
  position:absolute;left:0;bottom:0;padding:5px 10px;
  background:var(--lemon);color:var(--night);
  font-family:var(--font-mono);font-size:11px;
}

/* accordion protocol */
[data-accordion]{display:grid;gap:8px}
[data-accordion-trigger]{
  display:flex;width:100%;align-items:center;justify-content:space-between;gap:12px;
  padding:14px 16px;text-align:left;
  background:var(--panel);border:1px solid var(--line);border-radius:2px;
  font-size:15px;font-weight:700;color:var(--paper);
  transition:border-color .16s var(--ease),color .16s var(--ease);
}
[data-accordion-trigger]:hover{border-color:var(--cyan)}
[data-accordion-trigger][aria-expanded="true"]{border-color:var(--cyan);color:var(--cyan)}
[data-accordion-trigger]::after{content:"+";font-family:var(--font-mono);font-size:16px;color:var(--cyan)}
[data-accordion-trigger][aria-expanded="true"]::after{content:"–"}
[data-accordion-panel]{
  padding:14px 16px;border:1px solid var(--line);border-top:0;
  background:rgba(19,41,61,.55);
  font-size:14.5px;line-height:1.75;color:#C3D2DC;
}

/* ================= responsive ================= */
@media (max-width:1100px){
  .nav-link{padding:9px 8px;font-size:13.5px}
  .nav-link__index{display:none}
}

@media (max-width:960px){
  .command-bar__inner{flex-wrap:wrap}
  .primary-nav{display:none}
  .nav-toggle{display:inline-flex}
  .command-bar__actions .btn--ghost{display:none}
  .brand{margin-right:auto}
  .primary-nav[data-open]{
    display:grid;
    grid-template-columns:repeat(2,minmax(0,1fr));
    gap:4px;
    order:3;
    flex:1 0 100%;
    justify-content:stretch;
    width:100%;
    margin-top:6px;padding:12px 0 6px;
    border-top:1px solid var(--line);
  }
  .primary-nav[data-open] .nav-link{
    padding:12px;
    border:1px solid rgba(43,66,87,.8);
    background:rgba(19,41,61,.65);
    justify-content:flex-start;
  }
  .primary-nav[data-open] .nav-link__index{display:inline}
  .footer-grid{grid-template-columns:1fr 1fr}
  .footer-legal-links{margin-left:0}
}

@media (max-width:600px){
  .primary-nav[data-open]{grid-template-columns:1fr}
  .rail-text{display:none}
  .header-rail__inner{min-height:32px}
  .footer-grid{grid-template-columns:1fr}
  .footer-base{font-size:11.5px}
  .display-title{font-size:clamp(28px,8vw,40px)}
}

@media (max-width:420px){
  .brand__desc{display:none}
  .command-bar__actions .btn--primary{padding:8px 11px;font-size:12px}
}

/* ================= motion preferences ================= */
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  .rail-dot{animation:none;opacity:1}
  .scroll-progress__bar{transition:none}
  .skip-link{transition:none}
}