:root{
  color-scheme:light;
  --bg:#F7F8FA;
  --bg-panel:#FFFFFF;
  --bg-panel-2:#EEF1F5;
  --bg-panel-3:#F4F6F9;
  --border:#DFE3EA;
  --border-soft:#E8ECF1;
  --accent:#1F74F2;
  --accent-2:#4C93FF;
  --accent-dark:#1257C4;
  --text:#0F1726;
  --text-muted:#5A6475;
  --text-faint:#8A93A3;
  --success:#16A06A;
  --warn:#D98A0B;
  --error:#D9363E;
  --white:#FFFFFF;
  --sea-deep:#0E2A4F;
  --sea-light:#1B4F8F;
  --sea-night:#081B35;
  --chrome-ink:#1A2230;
  --chrome-ink-2:#2B3547;
  --chrome-icon:#E7ECF4;
  --tl-red:#FF5F57;
  --tl-yellow:#FEBC2E;
  --tl-green:#28C840;
  --flag-red:#D72638;
  --flag-blue:#1F3B8C;
  --flag-white:#FFFFFF;
  --flag-black:#16181D;
  --flag-gold:#F3C531;
  --flag-edge:rgba(15,23,38,.16);
  --accent-a00:rgba(31,116,242,0);
  --accent-a03:rgba(31,116,242,.03);
  --accent-a07:rgba(31,116,242,.07);
  --accent-a08:rgba(31,116,242,.08);
  --accent-a10:rgba(31,116,242,.10);
  --accent-a14:rgba(31,116,242,.14);
  --accent-a28:rgba(31,116,242,.28);
  --accent-a32:rgba(31,116,242,.32);
  --accent2-a00:rgba(76,147,255,0);
  --accent2-a18:rgba(76,147,255,.18);
  --accent2-a30:rgba(76,147,255,.30);
  --accent2-a45:rgba(76,147,255,.45);
  --white-a00:rgba(255,255,255,0);
  --white-a12:rgba(255,255,255,.12);
  --white-a18:rgba(255,255,255,.18);
  --white-a30:rgba(255,255,255,.30);
  --white-a55:rgba(255,255,255,.55);
  --white-a75:rgba(255,255,255,.75);
  --ink-a04:rgba(15,23,38,.04);
  --ink-a10:rgba(15,23,38,.10);
  --ink-a14:rgba(15,23,38,.14);
  --ink-a22:rgba(15,23,38,.22);
  --success-a30:rgba(22,160,106,.30);
  --shadow-panel:0 1px 2px rgba(31,116,242,.06),0 18px 48px rgba(31,116,242,.10);
  --shadow-board:0 40px 96px rgba(31,116,242,.14),0 12px 30px rgba(14,42,79,.14);
  --shadow-window:0 28px 60px rgba(3,14,32,.46),0 4px 12px rgba(3,14,32,.24);
  --shadow-float-deep:0 22px 44px rgba(3,14,32,.34),0 4px 10px rgba(3,14,32,.20);
  --shadow-float-light:0 16px 40px rgba(31,116,242,.16),0 2px 6px rgba(31,116,242,.08);
  --shadow-cta:0 10px 24px rgba(31,116,242,.28),0 2px 4px rgba(31,116,242,.20);
  --shadow-mark:0 4px 10px rgba(31,116,242,.25);
  --font-display:Inter,'Noto Sans SC','PingFang SC','Microsoft YaHei',system-ui,sans-serif;
  --font-body:Inter,'Noto Sans SC','PingFang SC','Hiragino Sans','Microsoft YaHei',system-ui,sans-serif;
  --font-mono:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --r-xs:5px;
  --r-sm:8px;
  --r-md:12px;
  --r-lg:16px;
  --r-tile:18px;
  --r-xl:24px;
  --r-2xl:28px;
  --r-pill:999px;
  --r-round:50%;
  --page-w:1280px;
  --gutter:32px;
  --header-h:72px;
  --anchor-gap:88px;
  --toc-offset:16px;
  --toc-landing:100px;
  --size-body:16px;
  --size-small:14px;
  --size-caption:12px;
  --size-h1:clamp(52px,4.6vw,66px);
  --size-h2:clamp(28px,3.1vw,44px);
  --size-h3:24px;
  --size-button:17px;
  --weight-normal:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --weight-heavy:800;
  --weight-display:900;
  --leading-body:1.6;
  --leading-title:1.16;
  --tracking-title:-.02em;
  --space-section:80px;
  --ease-fast:.15s ease;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:var(--anchor-gap);scroll-behavior:smooth}
html.nav-open{overflow:hidden}
body{
  margin:0;font-family:var(--font-body);font-size:var(--size-body);line-height:var(--leading-body);
  color:var(--text);
  background:linear-gradient(180deg,var(--accent-a03) 0,var(--accent-a07) 760px,var(--accent-a00) 1180px) no-repeat,var(--bg);
  background-size:100% 1180px,auto;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
a{color:var(--accent);text-underline-offset:4px}
a:hover{color:var(--accent-dark)}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button:disabled{cursor:not-allowed}
img{max-width:100%;height:auto;display:block}
svg{flex-shrink:0}
p{margin:0}
ul,ol{margin:0;padding:0;list-style:none}
h1,h2,h3,h4{font-family:var(--font-display);text-wrap:balance;color:var(--text)}
h1{font-size:var(--size-h1);font-weight:var(--weight-display);line-height:1.1;letter-spacing:var(--tracking-title);margin:0 0 24px}
h2{font-size:var(--size-h2);font-weight:var(--weight-display);line-height:var(--leading-title);letter-spacing:var(--tracking-title);margin:0 0 24px}
h3{font-size:var(--size-h3);font-weight:var(--weight-heavy);line-height:1.3;margin:0 0 16px}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:var(--r-sm)}
[hidden]{display:none!important}
.no-break{white-space:nowrap}
.wrap{width:100%;max-width:calc(var(--page-w) + var(--gutter)*2);margin-inline:auto;padding-inline:var(--gutter)}
.section{padding-top:var(--space-section);padding-bottom:var(--space-section)}
.section>*+*{margin-top:24px}
.grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}
.grid>*{min-width:0}
.panel,.card{min-width:0;background:var(--bg-panel);border:1px solid var(--border-soft);border-radius:var(--r-lg);padding:28px;box-shadow:inset 0 1px 0 var(--white),var(--shadow-panel)}
.panel{border-radius:var(--r-2xl)}
.muted{color:var(--text-muted)}
.hl{color:var(--accent)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.prose{max-width:880px;min-width:0;overflow-wrap:break-word}
.prose p,.prose ul,.prose ol,.prose blockquote,.prose pre{margin-bottom:24px}
.prose h2{margin-top:56px}
.prose h3{margin-top:32px}
.prose ul{list-style:disc;padding-left:24px}
.prose ol{list-style:decimal;padding-left:24px}
.prose li+li{margin-top:8px}
code{font-family:var(--font-mono);overflow-wrap:anywhere;word-break:break-word;color:var(--accent-dark)}
pre{max-width:100%;overflow-x:auto;padding:24px;border:1px solid var(--border);border-radius:var(--r-md);background:var(--bg-panel-2)}
pre code{white-space:pre;overflow-wrap:normal;word-break:normal;color:var(--text)}
.sprite{position:absolute;width:0;height:0;overflow:hidden}
.ln{fill:none;stroke:currentColor;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round}
.skip{position:absolute;left:16px;top:-60px;z-index:50;padding:8px 14px;border-radius:var(--r-sm);background:var(--accent);color:var(--white);font-size:var(--size-small);font-weight:var(--weight-bold);text-decoration:none}
.skip:focus{top:12px}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:54px;
  padding:12px 32px;border:0;border-radius:var(--r-pill);font-size:var(--size-button);
  font-weight:var(--weight-bold);line-height:1.3;text-decoration:none;flex-shrink:0;white-space:nowrap;
  transition:transform var(--ease-fast),box-shadow var(--ease-fast),background-color var(--ease-fast);
}
.btn svg{width:16px;height:16px}
.btn--primary,.btn-primary{color:var(--white);background:linear-gradient(180deg,var(--accent-2),var(--accent));box-shadow:inset 0 1px 0 var(--white-a30),var(--shadow-cta)}
.btn--primary:hover,.btn-primary:hover{color:var(--white);transform:translateY(-1px)}
.btn--primary:active,.btn-primary:active{transform:translateY(0);background:var(--accent-dark)}
.btn--ghost{color:var(--text);background:var(--bg-panel-2);box-shadow:inset 0 0 0 1px var(--border-soft)}
.btn--ghost:hover{color:var(--text);background:var(--border-soft)}
.btn--small{min-height:44px;padding:10px 20px;font-size:var(--size-small)}
.btn:disabled{opacity:.55;transform:none}
.cta-row{display:flex;flex-wrap:wrap;gap:14px;margin-top:30px}
.topbar{position:relative;z-index:30}
.topbar__inner{width:min(var(--page-w),100% - 64px);margin:0 auto;height:var(--header-h);display:flex;align-items:center;gap:24px}
.brand{display:inline-flex;align-items:center;gap:10px;text-decoration:none;flex:none;color:var(--text)}
.brand:hover{color:var(--text)}
.brand__mark{width:34px;height:34px;flex:none;display:block;filter:drop-shadow(var(--shadow-mark))}
.brand__en{font-family:var(--font-display);font-size:21px;font-weight:var(--weight-heavy);letter-spacing:var(--tracking-title);color:var(--text)}
.brand__zh{font-size:var(--size-small);font-weight:var(--weight-medium);color:var(--text-muted);padding-left:10px;border-left:1px solid var(--border)}
.topnav{margin-left:auto}
.topnav__list{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:2px}
.topnav__link{display:inline-flex;align-items:center;gap:6px;min-height:32px;padding:8px 10px;border-radius:var(--r-sm);font-size:var(--size-small);font-weight:var(--weight-semibold);line-height:1;color:var(--text-muted);text-decoration:none;white-space:nowrap;transition:color var(--ease-fast),background-color var(--ease-fast)}
.topnav__link svg{width:16px;height:16px}
.topnav__link:hover{color:var(--text);background:var(--ink-a04)}
.topnav__link[aria-current="page"]{color:var(--accent)}
.topbar__actions{display:flex;align-items:center;gap:10px;flex:none}
.langbox{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-width:44px;width:auto;height:38px;padding:0 12px;border-radius:var(--r-pill);border:1px solid var(--border);background:var(--bg-panel);font:var(--weight-semibold) 13.5px/1 var(--font-body);color:var(--text-muted)}
.lang span{white-space:nowrap}
.lang svg{width:15px;height:15px}
.lang-menu{position:absolute;top:calc(100% + 8px);right:0;min-width:180px;padding:8px;border-radius:var(--r-md);border:1px solid var(--border);background:var(--bg-panel);box-shadow:var(--shadow-panel)}
.lang-menu a{display:flex;align-items:center;min-height:44px;padding:10px 12px;text-decoration:none;color:var(--text);border-radius:var(--r-sm)}
.lang-menu a:hover,.lang-menu a[aria-current]{background:var(--accent-a10);color:var(--accent-dark)}
.btn-login{display:inline-flex;align-items:center;justify-content:center;height:38px;padding:0 20px;border-radius:var(--r-pill);background:linear-gradient(180deg,var(--accent-2),var(--accent));box-shadow:inset 0 1px 0 var(--white-a30),0 6px 16px var(--accent-a28);color:var(--white);font-size:var(--size-small);font-weight:var(--weight-bold);text-decoration:none;white-space:nowrap}
.btn-login:hover{color:var(--white);background:linear-gradient(180deg,var(--accent),var(--accent-dark))}
.nav-toggle{display:none;align-items:center;justify-content:center;min-width:44px;min-height:44px;border:1px solid var(--border);border-radius:var(--r-md);background:var(--bg-panel)}
.nav-toggle svg{width:20px;height:20px}
.mobile-nav{display:none}
.nav-veil{position:fixed;inset:var(--header-h) 0 0;background:var(--ink-a22);z-index:0}
.site-footer{margin-top:64px;padding-top:56px;padding-bottom:32px;background:linear-gradient(150deg,var(--sea-deep),var(--sea-night));color:var(--white)}
.footer-grid{display:grid;grid-template-columns:1.2fr 1fr 1fr;gap:48px}
.footer-grid>*{min-width:0}
.site-footer .brand__en{color:var(--white)}
.site-footer p{max-width:360px;margin-top:20px;color:var(--white-a75)}
.site-footer h2{font-size:var(--size-body);letter-spacing:normal;color:var(--white);margin-bottom:16px}
.footer-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px 20px}
.site-footer a:not(.brand){display:inline-flex;align-items:center;min-height:28px;color:var(--white);text-decoration:none}
.site-footer a:hover{color:var(--white);text-decoration:underline}
.footer-languages{display:flex;flex-wrap:wrap;gap:12px 24px;padding-top:32px;padding-bottom:24px}
.footer-bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:16px;padding-top:24px;border-top:1px solid var(--white-a18);font-size:var(--size-small);color:var(--white-a75)}
.footer-legal{display:flex;flex-wrap:wrap;gap:16px}
.reveal{transition:opacity .6s ease,transform .6s ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:relative;display:block;min-width:0;min-height:120px;max-width:100%;overflow:hidden;margin-top:24px;margin-bottom:32px}
#server-status+*{margin-top:32px}
#server-status>*{min-width:0;max-width:100%}
.decorated,.stripe-halo{overflow-x:clip;max-width:100%}
body:has(.toc-tabs) section[id]{scroll-margin-top:var(--toc-landing)}
@media(max-width:1240px){
  .brand__zh{display:none}
  .topnav__link{padding:8px 7px}
  .topbar__inner{gap:16px}
}
@media(max-width:1024px){
  .topnav{display:none}
  .topbar__actions{margin-left:auto}
  .nav-toggle{display:inline-flex}
  .mobile-nav:not([hidden]){display:block;position:absolute;left:0;right:0;top:var(--header-h);z-index:2;padding:16px var(--gutter) 24px;background:var(--bg-panel);border-bottom:1px solid var(--border);max-height:calc(100dvh - var(--header-h));overflow-y:auto;overscroll-behavior:contain}
  .mobile-nav a{display:flex;align-items:center;width:100%;min-height:44px;padding:12px 16px;text-decoration:none;border-radius:var(--r-sm);gap:10px;color:var(--text)}
  .mobile-nav a[aria-current],.mobile-nav a:hover{color:var(--accent-dark);background:var(--accent-a10)}
  .mobile-nav svg{width:18px;height:18px}
  .mobile-nav__languages{border-top:1px solid var(--border);margin-top:12px;padding-top:12px}
}
@media(max-width:768px){
  :root{--size-h1:clamp(28px,6vw,40px);--space-section:48px}
  .grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .footer-grid{grid-template-columns:1fr 1fr;gap:32px}
  .footer-grid>div:first-child{grid-column:1/-1}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .topbar__inner{width:calc(100% - var(--gutter)*2);gap:8px}
  .topbar__actions{margin-left:auto;gap:6px}
  .brand{gap:7px}
  .brand__mark{width:30px;height:30px}
  .brand__en{font-size:18px}
  .lang{padding-inline:10px}
  .lang__name{display:none}
  .btn-login{padding-inline:14px}
  .grid,.footer-grid{grid-template-columns:minmax(0,1fr)}
  .footer-grid>div:first-child{grid-column:auto}
  .panel,.card{padding:24px}
  .btn{padding-inline:24px}
  .tilt,.decorative-tilt{transform:none!important}
  .decorated,.stripe-halo{max-width:100%;overflow-x:clip}
  .prose{max-width:100%}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none!important;transition:none!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}