:root{
  --bg:#F8F9FB;--panel:#FFFFFF;--panel-tint:#F6F8FC;--panel-2:#EEF1F6;--panel-2b:#E9EDF4;
  --border:#E1E5EC;--border-strong:#CDD3DD;--accent:#1E54D6;--accent-dark:#133B9E;--violet:#A855E8;
  --text:#111318;--muted:#5A6270;--success:#1F9D63;--warn:#C9820A;--error:#D13B3B;
  --accent-a06:rgba(30,84,214,.06);--accent-a10:rgba(30,84,214,.10);--accent-a16:rgba(30,84,214,.16);--accent-a28:rgba(30,84,214,.28);
  --ink-a04:rgba(17,19,24,.04);--ink-a06:rgba(17,19,24,.06);--ink-a20:rgba(17,19,24,.20);--veil:rgba(17,19,24,.32);
  --hl-a18:rgba(255,255,255,.18);--hl-a70:rgba(255,255,255,.70);--grid-line:rgba(30,84,214,.07);--mask-solid:#000000;
  --flag-red:#D7263D;--flag-white:#FFFFFF;--flag-navy:#1B2A5E;--flag-blue:#2B3A78;
  --font-display:"Inter","Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Malgun Gothic","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --r-xs:4px;--r-sm:6px;--r-md:8px;--r-icon:5px;--r-pill:999px;--r-round:50%;
  --shadow-card:inset 0 1px 0 var(--panel),4px 12px 28px var(--accent-a10),0 1px 2px var(--ink-a06);
  --shadow-float:0 14px 28px var(--accent-a10),0 2px 6px var(--accent-a06);
  --grad-band:linear-gradient(90deg,var(--accent) 0%,var(--violet) 100%);
  --nav-h:64px;--container:1280px;--reading:820px;--gutter:32px;--toc-offset:140px;
  --weight-body:400;--weight-medium:500;--weight-bold:600;--weight-heavy:700;--weight-brand:800;--weight-display:900;
  --size-body:16px;--size-small:14px;--size-h1:clamp(52px,4.45vw,64px);--size-h2:clamp(28px,3.2vw,42px);--size-h3:24px;
  --ease-time:.2s;--reveal-time:.35s;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:calc(var(--nav-h) + 16px);scroll-behavior:smooth}
html.nav-open{overflow:hidden}
body{margin:0;font-family:var(--font-body);font-size:var(--size-body);font-weight:var(--weight-body);color:var(--text);background:var(--bg);line-height:1.65;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
[hidden]{display:none!important}
img{display:block;max-width:100%;height:auto}
svg{flex-shrink:0}
button,input,select,textarea{font:inherit}
button,summary{cursor:pointer}
button{color:inherit}
a{color:var(--accent);text-underline-offset:4px}
a:hover{color:var(--accent-dark)}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
h1,h2,h3,h4{font-family:var(--font-display);color:var(--text);overflow-wrap:break-word}
h1{font-size:var(--size-h1);font-weight:var(--weight-display);line-height:1.12;letter-spacing:-.02em;margin:0 0 24px;text-wrap:balance}
h2{font-size:var(--size-h2);font-weight:var(--weight-display);line-height:1.2;letter-spacing:-.02em;margin:0 0 24px;text-wrap:balance}
h3{font-size:var(--size-h3);font-weight:var(--weight-heavy);line-height:1.35;margin:0 0 16px}
p{margin:0 0 20px}
ul,ol{padding-inline-start:24px}
li+li{margin-top:6px}
strong{font-weight:var(--weight-heavy)}
code{font-family:var(--font-mono);font-size:.9em;overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:20px;background:var(--panel-2);border:1px solid var(--border);border-radius:var(--r-sm)}
pre code{overflow-wrap:normal;white-space:pre}
blockquote{margin-inline:0}
.wrap{max-width:var(--container);margin-inline:auto;padding-inline:var(--gutter);min-width:0;width:100%}
.reading-wrap{max-width:var(--reading);margin-inline:auto;padding-inline:var(--gutter);min-width:0;width:100%}
.section{padding-top:80px;padding-bottom:80px}
.section-head{text-align:center;max-width:820px;margin:0 auto 40px}
.muted{color:var(--muted)}
.mono{font-family:var(--font-mono)}
.no-break{white-space:nowrap}
.kw{color:var(--violet)}
.grid{display:grid;gap:24px}
.grid>*{min-width:0}
.panel,.card{min-width:0;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-md);padding:24px;box-shadow:inset 0 1px 0 var(--panel),0 8px 24px var(--accent-a06)}
.shell{background:radial-gradient(ellipse 60% 40% at 50% -6%,var(--accent-a06),transparent 70%),linear-gradient(180deg,var(--bg) 0%,var(--panel) 46%,var(--bg) 100%)}
.decorated{position:relative;isolation:isolate;overflow-x:clip}
.sprite{position:absolute;width:0;height:0;overflow:hidden}
.ico{width:16px;height:16px;display:block;flex:none}
.skip{position:absolute;left:16px;top:-64px;z-index:100;padding:8px 14px;border-radius:var(--r-sm);background:var(--text);color:var(--panel);text-decoration:none;font-size:var(--size-small)}
.skip:focus{top:12px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:44px;font-family:var(--font-body);font-weight:var(--weight-bold);text-decoration:none;white-space:nowrap;flex-shrink:0;border:1px solid transparent;border-radius:var(--r-pill);cursor:pointer;transition:background-color var(--ease-time),color var(--ease-time),box-shadow var(--ease-time)}
.btn-primary{height:50px;padding:0 32px;font-size:16.5px;color:var(--panel);background:var(--accent);box-shadow:inset 0 1px 0 var(--hl-a18),0 10px 24px var(--accent-a16)}
.btn-primary:hover,.btn-primary.is-hover{background:var(--accent-dark);color:var(--panel)}
.btn-secondary{padding:10px 22px;color:var(--accent);background:var(--panel);border-color:var(--accent-a28)}
.btn-secondary:hover{background:var(--accent-a06)}
.btn-login{min-height:38px;height:38px;padding:0 18px;font-size:14.5px;color:var(--accent);background:var(--accent-a06);border-color:var(--accent-a16)}
.btn-login:hover{background:var(--accent-a10);color:var(--accent-dark)}
.btn-link{height:50px;padding:0 4px;font-size:16.5px;color:var(--accent);background:transparent;border-radius:var(--r-xs)}
.btn-link:hover{color:var(--accent-dark)}
.btn-link .arr{display:inline-block;transition:transform var(--ease-time)}
.btn-link:hover .arr{transform:translateX(3px)}
.btn:disabled,.btn[aria-disabled="true"]{background:var(--panel-2);border-color:var(--border);color:var(--muted);box-shadow:none;cursor:not-allowed}
.btn.is-focus{outline:2px solid var(--accent);outline-offset:3px}
#site-header{position:relative;z-index:40;min-height:var(--nav-h)}
.topbar{height:var(--nav-h);position:relative;z-index:43}
.topbar-in{height:100%;display:flex;align-items:center;flex-wrap:nowrap}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--text);flex:none}
.brand:hover{color:var(--text)}
.brand-mark{width:32px;height:32px;display:block;flex:none}
.brand-en{font-family:var(--font-display);font-weight:var(--weight-brand);font-size:19px;letter-spacing:-.02em;line-height:1}
.brand-zh{font-size:13px;font-weight:var(--weight-medium);color:var(--muted);line-height:1;padding-left:10px;border-left:1px solid var(--border)}
.mainnav{margin-left:44px;flex:1;min-width:0}
.mainnav ul{display:flex;align-items:center;gap:28px;list-style:none;margin:0;padding:0}
.mainnav li{margin:0;flex:none}
.mainnav a{display:block;padding:8px 0;font-size:14.5px;font-weight:var(--weight-medium);color:var(--muted);text-decoration:none;white-space:nowrap;transition:color var(--ease-time)}
.mainnav a:hover{color:var(--text)}
.mainnav a[aria-current="page"]{color:var(--text);font-weight:var(--weight-heavy)}
.topbar-end{margin-left:auto;display:flex;align-items:center;gap:16px;flex-shrink:0}
.topbar-sep{width:1px;height:20px;background:var(--border);flex:none}
.lang-picker{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:32px;min-width:44px;width:auto;padding:6px 4px;border:0;background:none;font:inherit;font-size:14px;font-weight:var(--weight-medium);color:var(--muted);cursor:pointer;white-space:nowrap}
.lang span{white-space:nowrap}
.lang:hover{color:var(--text)}
.lang svg{width:16px;height:16px;display:block}
.lang-panel{position:absolute;right:0;top:calc(100% + 10px);z-index:48;width:180px;padding:6px;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-md);box-shadow:var(--shadow-float)}
.lang-panel a{display:flex;align-items:center;min-height:44px;padding:8px 12px;color:var(--text);text-decoration:none;border-radius:var(--r-xs)}
.lang-panel a:hover,.lang-panel a[aria-current]{background:var(--panel-2)}
.menu-toggle{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;padding:10px;background:transparent;border:1px solid var(--border);border-radius:var(--r-sm);color:var(--text)}
.menu-line{display:block;width:20px;height:2px;background:currentColor}
.menu-toggle[aria-expanded="true"]{background:var(--panel-2)}
.nav-drawer{display:none;position:fixed;top:var(--nav-h);left:0;right:0;height:calc(100dvh - var(--nav-h));max-height:calc(100dvh - var(--nav-h));overflow-y:auto;overscroll-behavior:contain;z-index:42;padding:16px var(--gutter) 32px;background:var(--panel);border-top:1px solid var(--border)}
.nav-drawer.is-open{display:block}
.nav-drawer ul{list-style:none;margin:0;padding:0}
.nav-drawer li{margin:0}
.nav-drawer a{display:flex;align-items:center;width:100%;min-height:44px;padding:12px 8px;text-decoration:none;color:var(--text);border-bottom:1px solid var(--border)}
.nav-drawer a[aria-current]{color:var(--accent);font-weight:var(--weight-heavy)}
.drawer-languages{margin-top:20px;border-top:1px solid var(--border)}
.nav-veil{position:fixed;inset:var(--nav-h) 0 0;z-index:41;background:var(--veil);border:0;width:100%;padding:0;display:none}
.nav-veil.is-open{display:block}
.site-footer{background:var(--panel-2);border-top:1px solid var(--border);padding-top:56px;padding-bottom:24px;margin-top:56px}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:40px}
.footer-grid>*{min-width:0}
.footer-brand p{max-width:320px;color:var(--muted);font-size:var(--size-small);margin-top:20px}
.footer-title{font-size:var(--size-small);font-weight:var(--weight-heavy);margin:0 0 14px}
.footer-links{list-style:none;padding:0;margin:0;display:grid;gap:4px}
.footer-links li{margin:0}
.footer-links a{display:inline-flex;align-items:center;min-height:28px;font-size:var(--size-small);color:var(--muted);text-decoration:none;overflow-wrap:anywhere}
.footer-links a:hover{color:var(--accent)}
.footer-bottom{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:16px;border-top:1px solid var(--border);padding-top:24px;margin-top:36px;font-size:13px;color:var(--muted)}
.footer-legal{display:flex;gap:18px;flex-wrap:wrap}
.footer-legal a{color:var(--muted);min-height:24px;display:inline-flex;align-items:center}
.reveal{transition:opacity var(--reveal-time),transform var(--reveal-time)}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
.stat-number,[data-stat]{display:inline-block;font-family:var(--font-mono);font-variant-numeric:tabular-nums;min-width:3ch;text-align:right}
#server-status{display:block;position:relative;min-height:80px;max-width:100%;overflow:hidden;margin-top:24px;margin-bottom:32px}
#server-status>*{min-width:0;max-width:100%}
#server-status+*{margin-top:32px}
@media(max-width:1280px){
  .mainnav{margin-left:32px}
  .mainnav ul{gap:20px}
  .brand-zh{display:none}
}
@media(max-width:1180px){
  .mainnav{display:none}
  .topbar-end{margin-left:auto}
  .menu-toggle{display:inline-flex}
}
@media(min-width:1181px){
  .nav-drawer.is-open,.nav-veil.is-open{display:none}
}
@media(max-width:768px){
  :root{--size-h1:clamp(28px,6vw,40px);--size-h2:clamp(26px,5vw,34px)}
  .section{padding-top:48px;padding-bottom:48px}
  .footer-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:28px}
}
@media(max-width:640px){
  :root{--gutter:18px}
  .no-break{white-space:normal}
  .topbar-end{gap:8px;margin-left:auto}
  .topbar-sep{display:none}
  .brand{gap:7px}
  .brand-en{font-size:16px}
  .brand-mark{width:28px;height:28px}
  .btn-login{padding-inline:12px;font-size:13px}
  .lang{font-size:12px;gap:3px}
  .lang svg{width:13px;height:13px}
  .tilt,.tilt-card{transform:none}
  .decorated>*{max-width:100%}
  .footer-grid{grid-template-columns:minmax(0,1fr)}
  .footer-bottom{align-items:flex-start;flex-direction:column}
}
@media(max-width:359px){
  .topbar-end{gap:4px}
  .brand-en{font-size:14px}
  .brand-mark{width:24px;height:24px}
  .lang{font-size:11px;padding-inline:2px}
  .lang svg{display:none}
  .btn-login{padding-inline:9px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{transition:none!important;animation:none!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}