:root{
  color-scheme:light;
  --bg:#E6EBF6;
  --bg-top:#DCE4F4;
  --bg-bottom:#EBEFF8;
  --panel:#F6F8FD;
  --panel-2:#D9E0F0;
  --border:#C5CFE5;
  --accent:#17924F;
  --accent-dark:#0E6B39;
  --cobalt:#2F62D9;
  --text:#14213D;
  --muted:#56627E;
  --success:#1D9A6C;
  --warn:#C98A0B;
  --error:#D2453B;
  --white:#FFFFFF;
  --clear:transparent;
  --card-top:#12244A;
  --card-bot:#1B3566;
  --navy-hover:#1E2F55;
  --on-dark:#FFFFFF;
  --on-dark-muted:rgba(205,217,242,.74);
  --line:rgba(197,207,229,.72);
  --glass:rgba(246,248,253,.75);
  --glass-soft:rgba(246,248,253,.55);
  --chip-bg:rgba(246,248,253,.72);
  --hl:rgba(255,255,255,.78);
  --hl-dark:rgba(255,255,255,.14);
  --accent-6:rgba(23,146,79,.06);
  --accent-12:rgba(23,146,79,.12);
  --accent-16:rgba(23,146,79,.16);
  --ok-ring:rgba(29,154,108,.20);
  --cobalt-6:rgba(47,98,217,.06);
  --cobalt-10:rgba(47,98,217,.10);
  --cobalt-12:rgba(47,98,217,.12);
  --cobalt-16:rgba(47,98,217,.16);
  --cobalt-32:rgba(47,98,217,.32);
  --glow-green:rgba(29,154,108,.10);
  --glow-cobalt:rgba(47,98,217,.12);
  --floor:rgba(246,248,253,.92);
  --navy-14:rgba(18,36,74,.14);
  --navy-24:rgba(18,36,74,.24);
  --navy-40:rgba(18,36,74,.40);
  --ink-50:rgba(6,14,32,.50);
  --flag-red:#D8263A;
  --flag-white:#FFFFFF;
  --flag-navy:#1F2E6B;
  --flag-blue:#1D4FA3;
  --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;
  --weight-regular:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --weight-heavy:800;
  --weight-display:900;
  --size-xs:12px;
  --size-sm:14px;
  --size-body:16px;
  --size-lead:20px;
  --size-h1:clamp(52px,4.86vw,72px);
  --size-hero:70px;
  --size-h2:40px;
  --size-h3:24px;
  --r-card:28px;
  --r-win:16px;
  --r-block:13px;
  --r-bar:20px;
  --r-tile:10px;
  --r-flag:3.5px;
  --r-small:4px;
  --r-pill:999px;
  --r-circle:50%;
  --sh-card:0 30px 60px -30px var(--navy-40),0 22px 56px -14px var(--navy-14);
  --sh-float:0 14px 30px -12px var(--navy-24);
  --sh-soft:0 8px 22px -14px var(--navy-24);
  --gutter:24px;
  --content-width:1392px;
  --reading-width:840px;
  --header-height:64px;
  --anchor-offset:88px;
  --toc-offset:152px;
  --ease:200ms ease;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:var(--anchor-offset)}
html.nav-open{overflow:hidden}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--size-body);line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button,a,input,summary,select,textarea{-webkit-tap-highlight-color:var(--accent-12)}
button{border:0}
img,video{max-width:100%;height:auto;display:block}
svg{flex-shrink:0}
h1,h2,h3,h4,p{margin:0}
h1,h2,h3{font-family:var(--font-display);text-wrap:balance;overflow-wrap:break-word}
h1{font-size:var(--size-h1);font-weight:var(--weight-display);line-height:1.1;letter-spacing:-.02em}
h2{font-size:var(--size-h2);font-weight:var(--weight-display);line-height:1.2;letter-spacing:-.02em}
h3{font-size:var(--size-h3);font-weight:var(--weight-heavy);line-height:1.3}
ul{list-style:none;margin:0;padding:0}
:focus-visible{outline:2px solid var(--cobalt);outline-offset:3px;border-radius:var(--r-small)}
[hidden]{display:none!important}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.no-break{white-space:nowrap}
.wrap{width:100%;max-width:calc(var(--content-width) + var(--gutter)*2);padding-inline:var(--gutter);margin-inline:auto;min-width:0}
.reading-wrap{width:100%;max-width:calc(var(--reading-width) + var(--gutter)*2);padding-inline:var(--gutter);margin-inline:auto;min-width:0}
.sec{padding-top:80px;padding-bottom:80px}
.stack>*+*{margin-top:24px}
.muted{color:var(--muted)}
.lead{font-size:var(--size-lead);color:var(--muted);line-height:1.5}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.grid{display:grid;gap:24px}
.grid>*{min-width:0}
.grid-three{grid-template-columns:repeat(3,minmax(0,1fr))}
.panel,.card{padding:28px;border-radius:var(--r-card);background:var(--panel);box-shadow:inset 0 1px 0 var(--hl),var(--sh-soft);min-width:0}
.panel-sunken{background:var(--panel-2)}
.prose{min-width:0;overflow-wrap:break-word}
.prose p,.prose ul,.prose ol{margin-block:20px}
.prose ul{list-style:disc;padding-left:24px}
.prose ol{padding-left:24px}
.prose h2{margin-block:48px 20px}
.prose h3{margin-block:32px 16px}
.prose a:not(.btn){color:var(--accent-dark);text-decoration:underline;text-underline-offset:3px}
code{font-family:var(--font-mono);overflow-wrap:anywhere;background:var(--panel-2);border-radius:var(--r-small);padding:2px 5px}
pre{max-width:100%;overflow-x:auto;padding:20px;border-radius:var(--r-win);background:var(--text);color:var(--on-dark);font-family:var(--font-mono)}
pre code{padding:0;background:var(--clear);color:inherit;overflow-wrap:normal;white-space:pre}
section[id]{scroll-margin-top:var(--anchor-offset)}
body:has(.toc-tabs) section[id]{scroll-margin-top:var(--toc-offset)}
#server-status{position:relative;display:block;min-height:160px;max-width:100%;overflow:hidden;margin-block:32px}
#server-status+*{margin-top:32px}
.reveal{transition:opacity .6s ease,transform .6s ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:52px;padding:12px 28px;border-radius:var(--r-pill);font-size:var(--size-body);font-weight:var(--weight-heavy);letter-spacing:.01em;flex-shrink:0;white-space:nowrap;transition:background-color var(--ease),transform var(--ease),box-shadow var(--ease)}
.btn svg{width:18px;height:18px}
.btn-primary{background:var(--text);color:var(--white);box-shadow:inset 0 1px 0 var(--hl-dark),0 16px 30px -14px var(--navy-40)}
.btn-primary:hover,.btn-primary.is-hover{background:var(--navy-hover);transform:translateY(-1px)}
.btn-secondary{background:var(--panel-2);color:var(--text);box-shadow:inset 0 0 0 1px var(--border),inset 0 1px 0 var(--hl)}
.btn-secondary:hover,.btn-secondary.is-hover{background:var(--panel)}
.btn:active{transform:translateY(0)}
.btn:disabled,.btn[aria-disabled="true"]{opacity:.55;cursor:not-allowed;transform:none}
.btn-small{min-height:40px;padding:8px 18px;font-size:var(--size-sm)}
.topbar,#site-header{position:relative;z-index:40}
.topbar-in{width:min(100% - 48px,1392px);margin:0 auto;min-height:var(--header-height);display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:24px;position:relative}
.brand{display:inline-flex;align-items:center;gap:10px;justify-self:start;min-height:44px;white-space:nowrap}
.brand img{width:34px;height:34px;flex:none}
.brand-en{font-family:var(--font-display);font-weight:var(--weight-display);font-size:18px;letter-spacing:-.01em;color:var(--text)}
.brand-zh{font-weight:var(--weight-medium);font-size:15px;color:var(--muted)}
.nav-track{display:flex;align-items:center;gap:2px;padding:4px;border-radius:var(--r-pill);background:var(--glass-soft);box-shadow:inset 0 0 0 1px var(--hl),var(--sh-soft);backdrop-filter:blur(10px)}
.nav-track ul{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:2px}
.nav-track a{display:block;padding:7px 13px;border-radius:var(--r-pill);font-size:var(--size-sm);font-weight:var(--weight-medium);line-height:20px;color:var(--muted);white-space:nowrap;transition:color var(--ease),background-color var(--ease)}
.nav-track a:hover{color:var(--text)}
.nav-track a[aria-current="page"]{background:var(--white);color:var(--text);font-weight:var(--weight-bold);box-shadow:0 4px 12px -6px var(--navy-24)}
.tools{display:flex;align-items:center;gap:10px;justify-self:end}
.language-control{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:38px;min-width:44px;width:auto;padding:0 12px;background:var(--clear);border-radius:var(--r-pill);font-size:var(--size-sm);font-weight:var(--weight-medium)}
.lang span{white-space:nowrap}
.lang svg{width:16px;height:16px}
.lang-caret{font-size:11px;color:var(--muted)}
.language-menu{position:absolute;top:calc(100% + 8px);right:0;width:190px;padding:8px;border-radius:var(--r-win);background:var(--panel);box-shadow:var(--sh-float);border:1px solid var(--border);z-index:45}
.language-menu a{display:flex;align-items:center;min-height:44px;padding:8px 12px;border-radius:var(--r-tile)}
.language-menu a:hover,.language-menu a[aria-current]{background:var(--accent-12);color:var(--accent-dark)}
.login{display:inline-flex;align-items:center;justify-content:center;min-height:38px;padding:0 20px;border-radius:var(--r-pill);background:var(--text);color:var(--white);font-size:var(--size-sm);font-weight:var(--weight-bold);white-space:nowrap;box-shadow:inset 0 1px 0 var(--hl-dark),0 10px 20px -12px var(--navy-40)}
.login:hover{background:var(--navy-hover)}
.menu-toggle{display:none;min-width:44px;min-height:44px;align-items:center;justify-content:center;border-radius:var(--r-pill);background:var(--panel);font-size:var(--size-lead)}
.mobile-drawer{display:none}
.nav-veil{position:fixed;inset:var(--header-height) 0 0;background:var(--navy-40);z-index:30}
.site-footer{background:var(--panel-2);border-top:1px solid var(--border);padding-top:56px;padding-bottom:28px}
.footer-grid{display:grid;grid-template-columns:1.15fr 1fr 1fr;gap:48px}
.footer-grid>*{min-width:0}
.footer-brand p{max-width:360px;margin-top:18px;color:var(--muted)}
.footer-heading{font-size:var(--size-body);font-weight:var(--weight-heavy);margin-bottom:12px}
.footer-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:4px 20px}
.footer-links a,.footer-languages a,.footer-legal a{display:inline-flex;align-items:center;min-height:32px;font-size:var(--size-sm)}
.footer-links a:hover,.footer-languages a:hover,.footer-legal a:hover{color:var(--accent-dark);text-decoration:underline}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 20px;margin-top:32px;padding-top:24px;border-top:1px solid var(--border)}
.footer-bottom{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px;margin-top:20px;color:var(--muted);font-size:var(--size-sm)}
.footer-legal{display:flex;gap:20px;flex-wrap:wrap}
@media(min-width:1181px) and (max-width:1400px){
  .topbar-in{gap:12px;grid-template-columns:auto 1fr auto}
  .nav-track{justify-self:center}
  .nav-track a{padding-inline:9px}
  .brand{gap:7px}
  .brand-zh{font-size:var(--size-xs)}
  .tools{gap:2px}
}
@media(max-width:1180px){
  .topbar-in{display:flex;gap:12px}
  .nav-track{display:none}
  .tools{margin-left:auto}
  .menu-toggle{display:inline-flex}
  .mobile-drawer:not([hidden]){display:block;position:absolute;top:100%;left:0;right:0;z-index:44;background:var(--panel);padding:16px var(--gutter) 24px;max-height:calc(100dvh - var(--header-height));overflow-y:auto;overscroll-behavior:contain;border-bottom:1px solid var(--border);box-shadow:var(--sh-float)}
  .mobile-drawer a{display:flex;align-items:center;width:100%;min-height:44px;padding:10px 16px;border-radius:var(--r-tile)}
  .mobile-drawer a[aria-current],.mobile-drawer a:hover{background:var(--accent-12);color:var(--accent-dark)}
  .drawer-languages{border-top:1px solid var(--border);margin-top:12px;padding-top:12px}
}
@media(max-width:768px){
  :root{--size-h1:clamp(28px,7vw,40px);--size-hero:40px;--size-h2:30px;--size-h3:22px;--gutter:20px}
  .grid-three{grid-template-columns:1fr}
  .sec{padding-top:48px;padding-bottom:48px}
  .footer-grid{grid-template-columns:1fr;gap:32px}
  .topbar-in{width:calc(100% - var(--gutter)*2)}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .tilt,.float-chip{transform:none}
  .stage-glow,.glow,.stripe-halo{max-width:100%}
  .brand-zh{display:none}
  .brand{gap:7px}
  .tools{gap:4px;margin-left:auto}
  .lang{padding-inline:7px}
  .login{padding-inline:14px}
  .panel,.card{padding:22px}
}
@media(max-width:360px){
  .brand-en{font-size:var(--size-body)}
  .brand img{width:28px;height:28px}
  .tools{gap:2px}
  .lang{padding-inline:4px;font-size:var(--size-xs)}
  .login{padding-inline:12px}
  .topbar-in{gap:4px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}