:root{
  --bg:#FAFAFD;--bg-deep:#F1F2FA;--panel:#FFFFFF;--panel-2:#F1F3FB;--panel-soft:#F7F8FD;--glass:rgba(255,255,255,.74);
  --border:#E4E6F0;--border-strong:#D6DAE8;--accent:#2D5DF2;--accent-dark:#1D3FBF;--accent-mid:#5B5DF4;--violet:#8B5CF6;--violet-ink:#6A3FD9;--violet-soft:#F2EDFF;--violet-face:#EEE9FE;--node-face:#EDF1FE;--plan-a:#F1F4FF;--plan-b:#F5F1FF;
  --accent-wash:rgba(45,93,242,.08);--accent-wash-2:rgba(45,93,242,.13);--accent-line:rgba(45,93,242,.22);--accent-line-soft:rgba(45,93,242,.14);
  --violet-wash:rgba(139,92,246,.07);--violet-wash-2:rgba(139,92,246,.20);--violet-line:rgba(139,92,246,.30);--violet-shadow:rgba(139,92,246,.35);
  --line-a:rgba(45,93,242,.55);--line-b:rgba(139,92,246,.55);--dash:#BCC1D4;
  --text:#121528;--text-muted:#5A6078;--text-faint:#8D93A9;--wordmark:#9298AE;
  --success:#16A36A;--success-ink:#0F7A4F;--success-wash:rgba(22,163,106,.10);--success-ring:rgba(22,163,106,.18);--warn:#D98A12;--error:#D93A45;
  --white:#FFFFFF;--highlight:rgba(255,255,255,.95);--gloss:rgba(255,255,255,.18);--glow-violet:rgba(139,92,246,.12);--glow-blue:rgba(45,93,242,.07);
  --shadow-tint:rgba(45,93,242,.10);--shadow-tint-strong:rgba(45,93,242,.16);--shadow-ink:rgba(18,21,40,.05);--shadow-ink-strong:rgba(18,21,40,.22);--cta-glow:rgba(45,93,242,.55);--veil:rgba(18,21,40,.22);
  --flag-red:#D52B3A;--flag-blue:#253A80;--flag-white:#FFFFFF;--clear:transparent;
  --r-xs:2px;--r-sm:8px;--r-md:10px;--r-lg:12px;--r-bar:16px;--r-xl:24px;--r-pill:999px;--r-circle:50%;
  --font-display:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Apple SD Gothic Neo","Malgun Gothic","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Apple SD Gothic Neo","Malgun Gothic","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --weight-normal:400;--weight-medium:500;--weight-semibold:600;--weight-bold:700;--weight-display:800;
  --size-body:16px;--size-small:14px;--size-caption:12px;--size-h1:clamp(52px,5vw,66px);--size-h2:clamp(30px,3.5vw,44px);--size-h3:24px;
  --gutter:24px;--content-width:1200px;--reading-width:800px;--header-height:80px;--anchor-offset:96px;--toc-offset:156px;
  --shadow-card:inset 0 1px 0 var(--highlight),0 20px 60px -28px var(--shadow-tint);
  --ease:ease;--speed:.2s;--reveal-speed:.35s;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:var(--anchor-offset)}
body{margin:0;position:relative;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--size-body);line-height:1.5;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
a{color:inherit;text-decoration:none}
img{display:block;max-width:100%;height:auto}
svg{flex-shrink:0}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button:disabled{cursor:not-allowed}
ul{list-style:none;margin:0;padding:0}
p,h1,h2,h3,h4,figure,blockquote{margin:0}
h1,h2,h3{font-family:var(--font-display);text-wrap:balance;overflow-wrap:break-word}
h1{font-size:var(--size-h1);line-height:1.12;font-weight:var(--weight-display);letter-spacing:-.02em}
h2{font-size:var(--size-h2);line-height:1.2;font-weight:var(--weight-display);letter-spacing:-.02em}
h3{font-size:var(--size-h3);line-height:1.3;font-weight:var(--weight-bold)}
:where(a,button,summary,input,select,textarea,[tabindex]):focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:var(--r-sm)}
[hidden]{display:none!important}
.wrap{width:100%;max-width:var(--content-width);margin-inline:auto;padding-inline:var(--gutter)}
.reading-wrap{width:100%;max-width:var(--reading-width);margin-inline:auto;padding-inline:var(--gutter)}
.section{padding-top:88px;padding-bottom:88px}
.page-head{padding-top:128px;padding-bottom:48px}
.page-head p{margin-top:20px;max-width:760px;font-size:18px;color:var(--text-muted);line-height:1.8}
.section-head{margin-bottom:32px}
.section-head p{margin-top:16px;max-width:760px;color:var(--text-muted);line-height:1.8}
.grid-two,.grid-three{display:grid;gap:24px}
.grid-two{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid-three{grid-template-columns:repeat(3,minmax(0,1fr))}
:where(.grid-two,.grid-three)>*,:where(main,article,section,aside){min-width:0}
.card{padding:24px;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-lg);box-shadow:var(--shadow-card)}
.panel{padding:40px;background:var(--panel-2);border-radius:var(--r-xl)}
.muted{color:var(--text-muted)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.no-break{white-space:nowrap}
.kw{background-image:linear-gradient(90deg,var(--accent),var(--violet));-webkit-background-clip:text;background-clip:text;color:var(--clear);-webkit-text-fill-color:var(--clear);padding-right:.03em}
.kw-a{background-image:linear-gradient(90deg,var(--accent),var(--accent-mid))}
.kw-b{background-image:linear-gradient(90deg,var(--accent-mid),var(--violet))}
.prose{line-height:1.9;overflow-wrap:break-word}
.prose p,.prose ul,.prose ol,.prose pre,.prose blockquote{margin-block:18px}
.prose ul{list-style:disc;padding-left:24px}
.prose ol{padding-left:24px}
.prose h2{margin-top:48px;margin-bottom:20px}
.prose h3{margin-top:28px;margin-bottom:14px}
.prose a:not(.btn){color:var(--accent-dark);text-decoration:underline;text-underline-offset:4px}
code{font-family:var(--font-mono);overflow-wrap:anywhere;background:var(--panel-2);border-radius:var(--r-xs);padding:2px 5px}
pre{max-width:100%;overflow-x:auto;background:var(--panel-2);border:1px solid var(--border);border-radius:var(--r-md);padding:20px}
pre code{padding:0;background:var(--clear);overflow-wrap:normal;white-space:pre}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:48px;padding:0 20px 0 24px;border:0;border-radius:var(--r-md);font-size:var(--size-body);font-weight:var(--weight-semibold);letter-spacing:-.005em;flex-shrink:0;white-space:nowrap;transition:background-color var(--speed) var(--ease),box-shadow var(--speed) var(--ease),transform var(--speed) var(--ease)}
.btn svg{width:20px;height:20px}
.btn-primary{background:var(--accent);color:var(--white);box-shadow:inset 0 1px 0 var(--gloss),0 12px 26px -12px var(--cta-glow)}
.btn-primary:hover,.btn-primary.is-hover{background:var(--accent-dark);transform:translateY(-1px)}
.btn-ghost,.btn-secondary{background:var(--panel);color:var(--accent);box-shadow:inset 0 0 0 1.5px var(--accent)}
.btn-ghost:hover,.btn-secondary:hover,.btn-ghost.is-hover{background:var(--accent-wash)}
.btn:active,.btn.is-active{transform:translateY(1px)}
.btn:disabled{background:var(--panel-2);color:var(--text-muted);box-shadow:inset 0 0 0 1px var(--border);transform:none}
.btn.is-focus{outline:2px solid var(--accent);outline-offset:3px}
.cta-row{display:flex;flex-wrap:wrap;justify-content:center;gap:16px;margin-bottom:20px}
.topbar{position:absolute;top:0;left:0;right:0;z-index:50;padding:12px 24px 0}
.bar{position:relative;z-index:53;max-width:1320px;height:56px;margin:0 auto;display:flex;align-items:center;flex-wrap:nowrap;gap:24px;padding:0 12px 0 20px;background:var(--glass);border:1px solid var(--border);border-radius:var(--r-bar);-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);box-shadow:inset 0 1px 0 var(--highlight),0 10px 28px -20px var(--shadow-tint-strong)}
.brand{display:inline-flex;align-items:center;gap:10px;flex-shrink:0}
.brand-mark{width:30px;height:30px;display:block}
.brand-en{font-family:var(--font-display);font-weight:var(--weight-display);font-size:18px;letter-spacing:-.025em;color:var(--text)}
.brand-zh{font-size:14px;font-weight:var(--weight-medium);color:var(--text-muted);letter-spacing:.01em}
.nav{margin-left:auto;flex:1;min-width:0}
.nav-list{display:flex;align-items:center;justify-content:flex-end;list-style:none;margin:0;padding:0;font-size:14.5px;color:var(--text-muted)}
.nav-list li{display:flex;align-items:center;flex-shrink:0}
.nav-list li+li::before{content:"·";margin:0 11px;color:var(--text-faint);font-weight:var(--weight-bold)}
.nav-list a{display:inline-flex;align-items:center;min-height:32px;padding:6px 2px;white-space:nowrap;transition:color var(--speed) var(--ease)}
.nav-list a:hover{color:var(--text)}
.nav-list a[aria-current="page"]{color:var(--text);font-weight:var(--weight-semibold)}
.bar-end{display:flex;align-items:center;gap:10px;padding-left:18px;border-left:1px solid var(--border);flex-shrink:0}
.lang-wrap{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;height:36px;min-width:44px;width:auto;padding:0 10px;border:0;background:var(--clear);font-size:14px;color:var(--text-muted);border-radius:var(--r-sm);white-space:nowrap}
.lang span{white-space:nowrap}
.lang:hover{color:var(--text)}
.lang-caret{font-size:11px;color:var(--text-faint)}
.lang-panel{position:absolute;right:0;top:calc(100% + 10px);z-index:60;min-width:176px;padding:8px;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-lg);box-shadow:0 20px 48px -16px var(--shadow-tint-strong)}
.lang-panel a{display:flex;align-items:center;min-height:44px;padding:8px 12px;border-radius:var(--r-sm);color:var(--text-muted);white-space:nowrap}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--accent-wash);color:var(--accent-dark)}
.login{display:inline-flex;align-items:center;justify-content:center;gap:6px;height:36px;min-height:36px;padding:0 16px;border-radius:var(--r-sm);background:var(--panel);font-size:14px;font-weight:var(--weight-semibold);color:var(--text);white-space:nowrap;box-shadow:inset 0 0 0 1px var(--border-strong),0 4px 10px -6px var(--shadow-tint-strong);transition:box-shadow var(--speed) var(--ease),color var(--speed) var(--ease)}
.login:hover{color:var(--accent-dark);box-shadow:inset 0 0 0 1px var(--accent-line),0 6px 14px -8px var(--shadow-tint-strong)}
.menu-toggle{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;border:0;border-radius:var(--r-sm);background:var(--clear);color:var(--text)}
.menu-line{display:block;width:20px;height:2px;background:currentColor;border-radius:var(--r-xs)}
.mobile-drawer{display:none}
.nav-veil{display:none}
html.nav-open{overflow:hidden}
.site-footer{padding-top:64px;padding-bottom:32px;background:linear-gradient(180deg,var(--bg),var(--panel-2));border-top:1px solid var(--border)}
.footer-grid{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:48px}
.footer-brand p{max-width:340px;margin-top:20px;color:var(--text-muted);font-size:14px;line-height:1.8}
.footer-heading{font-size:14px;font-weight:var(--weight-semibold);margin-bottom:16px}
.footer-links{display:flex;flex-wrap:wrap;gap:8px 18px}
.footer-links a,.footer-languages a,.footer-legal a{display:inline-flex;align-items:center;min-height:32px;font-size:14px;color:var(--text-muted)}
.footer-links a:hover,.footer-languages a:hover,.footer-legal a:hover{color:var(--accent-dark)}
.footer-languages{display:flex;flex-wrap:wrap;gap:10px 24px;margin-top:40px;padding-top:24px;border-top:1px solid var(--border)}
.footer-languages a[aria-current="true"]{color:var(--accent-dark)}
.footer-bottom{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:16px;margin-top:24px;font-size:12px;color:var(--text-muted)}
.footer-legal{display:flex;flex-wrap:wrap;gap:20px}
.reveal{transition:opacity var(--reveal-speed) var(--ease),transform var(--reveal-speed) var(--ease)}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{display:block;position:static;min-width:0;max-width:100%;overflow:hidden;margin-top:24px;margin-bottom:32px}
#server-status>*{min-width:0;max-width:100%}
#server-status+*{margin-top:32px}
.decorated,.tilt-shell,.stripe-halo-shell{position:relative;overflow-x:clip;max-width:100%}
@media(min-width:1101px) and (max-width:1300px){
  .bar{gap:16px}.nav-list{font-size:13px}.nav-list li+li::before{margin-inline:7px}.bar-end{gap:6px;padding-left:12px}
}
@media(max-width:1100px){
  .nav{display:none}
  .bar-end{margin-left:auto;border-left:0;padding-left:0;gap:6px}
  .menu-toggle{display:inline-flex}
  .mobile-drawer{position:fixed;z-index:52;inset:var(--header-height) 0 auto;height:calc(100dvh - var(--header-height));max-height:calc(100dvh - var(--header-height));overflow-y:auto;overscroll-behavior:contain;background:var(--panel);padding:16px var(--gutter) 32px;border-top:1px solid var(--border)}
  .mobile-drawer:not([hidden]){display:block}
  .mobile-drawer a{display:flex;align-items:center;justify-content:space-between;width:100%;min-height:48px;padding:12px 16px;border-radius:var(--r-sm);color:var(--text-muted)}
  .mobile-drawer a:hover,.mobile-drawer a[aria-current]{background:var(--accent-wash);color:var(--accent-dark)}
  .drawer-languages{display:block;border-top:1px solid var(--border);margin-top:16px;padding-top:16px}
  .nav-veil{position:fixed;z-index:51;inset:var(--header-height) 0 0;background:var(--veil);border:0}
  .nav-veil:not([hidden]){display:block}
  .footer-grid{gap:24px}
}
@media(max-width:768px){
  :root{--size-h1:clamp(28px,7vw,40px);--size-h2:clamp(26px,5vw,34px);--gutter:20px}
  .section{padding-top:56px;padding-bottom:56px}
  .page-head{padding-top:112px;padding-bottom:32px}
  .grid-three{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:1/-1}
  .panel{padding:24px}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .topbar{padding:12px 12px 0}
  .bar{padding:0 6px 0 12px;gap:8px}
  .brand{gap:7px}.brand-en{font-size:16px}.brand-mark{width:26px;height:26px}
  .bar-end{margin-left:auto;gap:2px}
  .lang{font-size:12px;padding-inline:5px}
  .login{font-size:13px;padding-inline:10px}
  .grid-two,.footer-grid{grid-template-columns:1fr}
  .card{padding:20px}
  .tilt,.tilt-shell{transform:none}
  .decorated,.stripe-halo-shell{max-width:100%;overflow-x:clip}
  .footer-grid{gap:32px}
  .footer-brand{grid-column:auto}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{transition-duration:0s!important;animation-duration:0s!important;animation-iteration-count:1!important}
  .reveal,.reveal.pending,.reveal.shown{opacity:1;transform:none}
}