:root{
  color-scheme:light;
  --bg:#F4F3F0;
  --bg-top:#F8F7F5;
  --bg-bottom:#EEECE7;
  --bg-panel:#FFFFFF;
  --bg-panel-2:#EAE8E3;
  --border:#DCD8D0;
  --border-strong:#C7C1B6;
  --split:#BDB7AB;
  --accent:#C0582A;
  --accent-light:#CB6638;
  --accent-dark:#8E3C19;
  --text:#1A1917;
  --text-muted:#6B675F;
  --text-faint:#9A958B;
  --success:#2F8A57;
  --warn:#B9820F;
  --error:#C23A34;
  --copper-soft:#C98C6B;
  --sage:#8E9B89;
  --slate:#6E7681;
  --slab-a:#ECE9E3;
  --slab-b:#D8D3C9;
  --on-accent:#FFFFFF;
  --lead:#A9A397;
  --clear:rgba(255,255,255,0);
  --hi:rgba(255,255,255,.92);
  --hi-soft:rgba(255,255,255,.6);
  --hi-cta:rgba(255,255,255,.26);
  --beam:rgba(255,255,255,.6);
  --beam-soft:rgba(255,255,255,.22);
  --glass:rgba(255,255,255,.46);
  --glass-line:rgba(255,255,255,.8);
  --accent-a00:rgba(192,88,42,0);
  --accent-a06:rgba(192,88,42,.06);
  --accent-a10:rgba(192,88,42,.10);
  --accent-a12:rgba(192,88,42,.12);
  --accent-a16:rgba(192,88,42,.16);
  --accent-dark-a35:rgba(142,60,25,.35);
  --sage-a22:rgba(142,155,137,.24);
  --ink-a06:rgba(26,25,23,.06);
  --ink-a10:rgba(26,25,23,.10);
  --ink-a14:rgba(26,25,23,.14);
  --cube-top-a:#FFFFFF;
  --cube-top-b:#ECEAE5;
  --cube-left-a:#E2DFD8;
  --cube-left-b:#D8D4CC;
  --cube-right-a:#D3CFC6;
  --cube-right-b:#C8C3B9;
  --tray-top:#DCD8D0;
  --tray-left:#C9C4BA;
  --tray-right:#B9B3A8;
  --cell-top-a:#FDFCFA;
  --cell-top-b:#EFEDE8;
  --cell-left-a:#EDEAE4;
  --cell-left-b:#DFDBD3;
  --cell-right-a:#D9D5CC;
  --cell-right-b:#CBC6BC;
  --eng-top:#8C857A;
  --eng-left:#7A746A;
  --eng-right:#69635A;
  --eng-hi:rgba(255,255,255,.92);
  --eng-hi-soft:rgba(255,255,255,.5);
  --sock-a:#D2CDC3;
  --sock-b:#F2F0EB;
  --bolt:#A87D65;
  --mesh:rgba(70,62,52,.22);
  --shade-0:rgba(60,50,40,0);
  --shade-1:rgba(60,50,40,.10);
  --cube-outline:rgba(90,80,68,.24);
  --flag-red:#B8443B;
  --flag-blue:#2E3F6C;
  --flag-white:#FBFAF7;
  --veil:rgba(26,25,23,.24);
  --font-display:'Iowan Old Style','Palatino Linotype',Palatino,Georgia,'Songti SC','STSong','Noto Serif SC','Noto Serif CJK SC',serif;
  --font-body:Inter,'Noto Sans SC',-apple-system,'PingFang SC','Hiragino Sans','Microsoft YaHei','Malgun Gothic',sans-serif;
  --font-mono:'JetBrains Mono',ui-monospace,'SFMono-Regular',Menlo,Consolas,'Noto Sans SC',monospace;
  --r-xs:4px;
  --r-sm:8px;
  --r-md:10px;
  --r-lg:14px;
  --r-pill:999px;
  --r-circle:50%;
  --shadow-lift:inset 0 1px 0 var(--hi),0 1px 2px var(--ink-a06),0 16px 36px -14px var(--accent-a12);
  --shadow-float:inset 0 1px 0 var(--hi),0 2px 6px var(--ink-a06),0 22px 44px -16px var(--accent-a16);
  --nav-h:72px;
  --hero-h:clamp(720px,calc(100svh - 120px),860px);
  --gutter:32px;
  --content-w:1280px;
  --reading-w:800px;
  --toc-offset:88px;
  --anchor-offset:164px;
  --size-body:16px;
  --size-small:14px;
  --size-label:12px;
  --size-h1:clamp(52px,4.6vw,66px);
  --size-h2:clamp(28px,3vw,40px);
  --size-h3:24px;
  --weight-normal:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --ease: cubic-bezier(.2,.65,.3,1);
  --duration:.2s;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:var(--toc-offset);scroll-behavior:smooth}
body{
  margin:0;color:var(--text);font-family:var(--font-body);font-size:var(--size-body);line-height:1.6;
  -webkit-font-smoothing:antialiased;background-color:var(--bg);
  background-image:linear-gradient(180deg,var(--bg-top),var(--bg-bottom));
  background-size:100% calc(var(--nav-h) + var(--hero-h));background-repeat:no-repeat;overflow-x:clip;
}
html.nav-open{overflow:hidden}
[hidden]{display:none!important}
a{color:inherit;text-underline-offset:4px}
button,input,select,textarea{font:inherit;color:inherit}
button,summary{cursor:pointer}
button{border:0}
img,video{display:block;max-width:100%;height:auto}
svg{vertical-align:middle}
a,button,summary,select{touch-action:manipulation}
:where(a,button,summary,input,select,textarea,[tabindex]):focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:var(--r-xs)}
::selection{background:var(--accent-a16);color:var(--text)}
h1,h2,h3,h4{font-family:var(--font-display);font-weight:var(--weight-normal);line-height:1.2;text-wrap:balance;overflow-wrap:break-word}
h1{font-size:var(--size-h1);line-height:1.1;letter-spacing:-.02em}
h2{font-size:var(--size-h2);margin:0 0 24px}
h3{font-size:var(--size-h3);margin:0 0 16px}
p{margin:0 0 20px}
small{font-size:var(--size-small)}
strong{font-weight:var(--weight-semibold)}
code{font-family:var(--font-mono);overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:24px;border:1px solid var(--border);border-radius:var(--r-sm);background:var(--bg-panel-2)}
pre code{overflow-wrap:normal;white-space:pre}
table{border-collapse:collapse}
hr{border:0;border-top:1px solid var(--border);margin:32px 0}
main{position:relative;z-index:1}
:where(.wrap,.grid,.panel,.card,.prose,.hero-copy)>*{min-width:0}
.wrap{width:100%;max-width:var(--content-w);margin-inline:auto;padding-inline:var(--gutter);min-width:0}
.reading-wrap{max-width:var(--reading-w)}
.section{padding-top:80px;padding-bottom:80px}
.grid{display:grid;gap:24px;min-width:0}
.grid--three{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--five{grid-template-columns:repeat(5,minmax(0,1fr))}
.panel,.card{min-width:0;padding:32px;background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-lg);box-shadow:var(--shadow-lift)}
.panel--sunken{background:var(--bg-panel-2);box-shadow:inset 0 1px 2px var(--ink-a06),inset 0 -1px 0 var(--hi)}
.mono,.kicker{font-family:var(--font-mono)}
.kicker{font-size:var(--size-label);letter-spacing:.08em;color:var(--text-muted)}
.muted{color:var(--text-muted)}
.no-break{white-space:nowrap}
.kw{color:var(--accent)}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
.svg-defs{position:absolute;width:0;height:0;overflow:hidden;pointer-events:none}
.decor-region{position:relative;overflow-x:clip}
.reveal{transition:opacity .35s var(--ease),transform .35s var(--ease)}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:relative;display:block;min-height:120px;overflow:hidden;margin-top:24px;margin-bottom:32px;max-width:100%}
#server-status>*{min-width:0;max-width:100%}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:10px;height:52px;min-height:44px;
  padding:0 26px;border:1px solid var(--clear);border-radius:var(--r-md);font-size:var(--size-body);
  font-weight:var(--weight-medium);text-decoration:none;white-space:nowrap;flex-shrink:0;
  transition:background-color var(--duration),border-color var(--duration),box-shadow var(--duration);
}
.btn svg{width:16px;height:16px;flex-shrink:0}
.btn-primary{
  color:var(--on-accent);background-color:var(--accent);background-image:linear-gradient(180deg,var(--accent-light),var(--accent));
  box-shadow:inset 0 1px 0 var(--hi-cta),inset 0 -1px 0 var(--accent-dark-a35),0 2px 4px var(--accent-a16),0 16px 34px -10px var(--accent-a12);
}
.btn-primary:hover,.btn-primary.is-hover{background-image:linear-gradient(180deg,var(--accent),var(--accent-dark))}
.btn-primary:active,.btn-primary.is-pressed{background-image:none;background-color:var(--accent-dark);box-shadow:inset 0 2px 4px var(--accent-dark-a35)}
.btn-ghost,.btn-secondary{color:var(--text);background:var(--clear);border-color:var(--border-strong)}
.btn-ghost:hover,.btn-secondary:hover{background:var(--bg-panel);border-color:var(--text-faint)}
.btn:disabled,.btn[aria-disabled="true"]{opacity:.5;cursor:not-allowed;pointer-events:none}
.btn-small{height:44px;padding-inline:18px;font-size:var(--size-small)}
.cta-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:36px}
#site-header{position:relative;z-index:50;min-height:var(--nav-h)}
.masthead{
  position:relative;z-index:53;height:var(--nav-h);display:flex;align-items:center;flex-wrap:nowrap;
  gap:40px;padding:0 64px;border-bottom:1px solid var(--border);box-shadow:0 1px 0 var(--hi-soft);
}
.brand{display:inline-flex;align-items:center;gap:10px;text-decoration:none;color:var(--text);flex-shrink:0;min-height:28px}
.brand-mark{display:block;width:28px;height:28px;flex-shrink:0}
.brand-en{font-weight:var(--weight-bold);font-size:var(--size-body);letter-spacing:.03em;white-space:nowrap}
.brand-zh{font-size:13px;font-weight:var(--weight-normal);color:var(--text-muted);padding-left:10px;border-left:1px solid var(--border)}
.nav{flex:1;min-width:0;display:flex;justify-content:center;height:100%}
.nav ul{display:flex;align-items:center;gap:28px;list-style:none;margin:0;padding:0;height:100%}
.nav li{height:100%}
.nav a{position:relative;display:flex;align-items:center;min-height:44px;height:100%;font-size:var(--size-small);color:var(--text-muted);text-decoration:none;white-space:nowrap;transition:color var(--duration)}
.nav a::after{content:"";position:absolute;left:0;right:0;bottom:-1px;height:2px;border-radius:var(--r-xs);background:var(--accent);transform:scaleX(0);transition:transform var(--duration)}
.nav a:hover{color:var(--text)}
.nav a[aria-current="page"]{color:var(--text);font-weight:var(--weight-medium)}
.nav a[aria-current="page"]::after{transform:scaleX(1)}
.nav-end{display:flex;align-items:center;gap:16px;flex-shrink:0}
.language{position:relative}
.lang{appearance:none;border:0;background:none;font:inherit;font-size:var(--size-small);color:var(--text-muted);display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:44px;min-width:44px;width:auto;padding:6px 4px;cursor:pointer}
.lang svg{width:16px;height:16px;flex-shrink:0}
.lang-label{white-space:nowrap}
.lang-panel{position:absolute;right:0;top:calc(100% + 8px);z-index:60;min-width:180px;padding:8px;background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-sm);box-shadow:var(--shadow-float)}
.lang-panel a{display:flex;align-items:center;width:100%;min-height:44px;padding:8px 12px;text-decoration:none;font-size:var(--size-small)}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--bg-panel-2);border-radius:var(--r-xs)}
.btn-login{display:inline-flex;align-items:center;justify-content:center;height:36px;min-height:36px;padding:0 18px;border-radius:var(--r-sm);background:var(--bg-panel);border:1px solid var(--border);box-shadow:var(--shadow-lift);color:var(--text);font-size:var(--size-small);font-weight:var(--weight-medium);text-decoration:none;white-space:nowrap}
.btn-login:hover{border-color:var(--border-strong)}
.menu-toggle{display:none;align-items:center;justify-content:center;min-width:44px;min-height:44px;background:var(--clear);color:var(--text);border:1px solid var(--border);border-radius:var(--r-sm)}
.menu-toggle svg{width:20px;height:20px;flex-shrink:0}
.menu-lines{fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round}
.nav-drawer{position:fixed;z-index:52;top:var(--nav-h);inset-inline:0;height:calc(100dvh - var(--nav-h));max-height:calc(100dvh - var(--nav-h));overflow-y:auto;overscroll-behavior:contain;background:var(--bg-panel);padding:16px var(--gutter) 32px;border-top:1px solid var(--border)}
.nav-drawer a{display:flex;align-items:center;width:100%;min-height:48px;padding:12px 16px;text-decoration:none;border-bottom:1px solid var(--border)}
.nav-drawer a[aria-current="page"]{border-left:2px solid var(--accent);background:var(--bg-panel-2)}
.drawer-languages{display:grid;grid-template-columns:1fr;margin-top:24px}
.nav-veil{position:fixed;z-index:51;top:var(--nav-h);inset-inline:0;bottom:0;background:var(--veil)}
.site-footer{position:relative;z-index:1;border-top:1px solid var(--border);box-shadow:inset 0 1px 0 var(--hi);background:var(--bg-panel-2);padding-top:56px;padding-bottom:24px}
.footer-grid{display:grid;grid-template-columns:1.35fr 1fr 1fr;gap:48px}
.footer-brand p{max-width:30em;margin-top:20px;color:var(--text-muted);font-size:var(--size-small)}
.footer-title{font-family:var(--font-mono);font-size:var(--size-label);color:var(--text-muted);margin:0 0 16px}
.footer-links{display:grid;gap:8px;list-style:none;margin:0;padding:0}
.footer-links a{display:inline-flex;align-items:center;min-height:28px;text-decoration:none;font-size:var(--size-small)}
.footer-links a:hover{text-decoration:underline}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 24px;margin-top:32px;padding-top:24px;border-top:1px solid var(--border)}
.footer-languages a{display:inline-flex;align-items:center;min-height:28px;font-size:var(--size-small)}
.footer-bottom{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:16px;margin-top:24px;font-size:var(--size-label);color:var(--text-muted)}
.footer-legal{display:flex;flex-wrap:wrap;gap:16px}
.footer-legal a{display:inline-flex;align-items:center;min-height:28px}
.prose{overflow-wrap:break-word}
.prose h2{margin-top:48px}
.prose h3{margin-top:32px}
.prose li{margin-bottom:8px}
.prose a{overflow-wrap:anywhere}
@media(min-width:961px){
  .nav-drawer,.nav-veil,.menu-toggle{display:none!important}
}
@media(max-width:1320px){
  .masthead{gap:24px;padding-inline:32px}
  .nav ul{gap:18px}
  .nav a{font-size:13px}
  .nav-end{gap:12px}
}
@media(max-width:1100px){
  .masthead{gap:16px;padding-inline:24px}
  .nav ul{gap:12px}
  .nav-end{gap:8px}
}
@media(max-width:960px){
  .nav{display:none}
  .nav-end{margin-left:auto}
  .menu-toggle{display:inline-flex}
  .footer-grid{grid-template-columns:1fr 1fr;gap:32px}
  .footer-brand{grid-column:1/-1}
}
@media(max-width:768px){
  :root{--gutter:20px;--size-h1:clamp(28px,8.4vw,40px);--size-h2:30px}
  body{background-size:100% 100%}
  .masthead{padding-inline:16px;gap:12px}
  .section{padding-top:48px;padding-bottom:48px}
  .grid--three{grid-template-columns:1fr}
  .grid--five{grid-template-columns:repeat(2,minmax(0,1fr))}
  .panel,.card{padding:24px}
  .footer-grid{gap:24px}
}
@media(max-width:640px){
  .no-break{white-space:normal}
  .tilt,.tilt-decor{transform:none}
  [data-parallax-decor],.stripe-halo{max-width:100%}
  .nav-end{margin-left:auto;gap:6px}
  .footer-grid{grid-template-columns:1fr}
  .footer-brand{grid-column:auto}
}
@media(max-width:480px){
  .lang-label{display:none}
  .brand{gap:8px}
  .brand-en{font-size:var(--size-small)}
  .brand-mark{width:26px;height:26px}
  .btn-login{padding-inline:12px;font-size:13px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{transition:none!important;animation:none!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}