:root{
  --bg:#E8E8F8;--bg-panel:#F8F8FE;--bg-panel-2:#DCDCF1;--border:#C8C9E6;
  --accent:#1F4CC4;--accent-dark:#14308A;--accent-2:#3A6BE3;--accent-soft:#DCE4FA;--accent-faint:#EEF2FD;
  --text:#161A3A;--text-muted:#5A5E80;--text-faint:#7F83A3;
  --success:#1E9668;--success-soft:#DCF1E8;--warn:#D9971A;--error:#CF3F48;
  --hero-top:#D9DAF4;--tint:#F0F0FB;--white:#FFFFFF;--clear:transparent;
  --candy-yellow:#F5C33B;--candy-yellow-lt:#FADB7E;--candy-yellow-soft:#FDF3D3;
  --candy-pink:#F08DB4;--candy-pink-lt:#F7BDD4;--candy-pink-dk:#E2709E;
  --candy-sky:#8FB8F2;--candy-sky-lt:#C3D8F8;--candy-sky-soft:#E4EEFC;
  --flag-red:#D62B3B;--flag-blue:#283C8E;--flag-green:#1D8A4E;--flag-white:#FFFFFF;
  --hi:rgba(255,255,255,.92);--hi-soft:rgba(255,255,255,.55);
  --frame-top:rgba(248,248,254,.80);--frame-bot:rgba(220,220,241,.74);--glow:rgba(248,248,254,.78);
  --line:rgba(31,76,196,.09);--line-strong:rgba(31,76,196,.18);--ring:rgba(22,26,58,.12);
  --shade-1:rgba(31,76,196,.06);--shade-2:rgba(31,76,196,.10);--shade-3:rgba(31,76,196,.14);
  --shade-cta:rgba(31,76,196,.36);--veil:rgba(22,26,58,.24);
  --r-section:48px;--r-xl:30px;--r-lg:22px;--r-md:16px;--r-sm:12px;--r-xs:8px;--r-mark:9px;--r-light:3px;--r-pill:999px;--r-circle:50%;
  --f-display:Georgia,"Songti SC","STSong","Noto Serif SC","Source Han Serif SC","Times New Roman",serif;
  --f-body:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --f-mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --wrap:1200px;--gutter:24px;--header-h:64px;--anchor-gap:80px;--toc-offset:80px;--chapter-offset:156px;
  --lift-card:inset 0 1px 0 var(--hi),0 0 0 1px var(--line),0 18px 40px -18px var(--shade-3),0 4px 12px -4px var(--shade-1);
  --ease:cubic-bezier(.2,.65,.3,1);--fast:.2s;--reveal-time:.35s;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:var(--anchor-gap);scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--f-body);font-size:16px;line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
[hidden]{display:none!important}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button{border:0;background:var(--clear)}
img{max-width:100%;height:auto;vertical-align:middle}
svg{display:block;flex-shrink:0}
ul{list-style:none;margin:0;padding:0}
p{margin:0}
h1,h2,h3,h4{margin:0 0 20px;text-wrap:balance;overflow-wrap:break-word}
h1{font-family:var(--f-display);font-size:clamp(52px,4.7vw,68px);line-height:1.12;letter-spacing:-.02em}
h2{font-family:var(--f-display);font-size:clamp(28px,3vw,40px);line-height:1.25}
h3{font-size:22px;line-height:1.35}
:where(a,button,summary,input,select,textarea,[tabindex]):focus-visible{outline:2px solid var(--accent);outline-offset:4px}
:where(button,summary){min-height:24px}
.no-break{white-space:nowrap}
.wrap{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gutter)}
.section{padding-top:80px;padding-bottom:80px}
.section-head{max-width:760px;margin-bottom:32px}
.section-head p,.muted{color:var(--text-muted)}
.grid{display:grid;gap:24px}
.grid>*{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:28px;border-radius:var(--r-lg);background:var(--bg-panel);box-shadow:var(--lift-card)}
.panel-secondary{background:var(--bg-panel-2)}
.prose{max-width:800px;min-width:0}
.prose p,.prose ul,.prose ol,.prose pre,.prose blockquote{margin-bottom:24px}
.prose ul{list-style:disc;padding-left:24px}
.prose h2{margin-top:52px}
.prose h3{margin-top:32px}
.prose a{color:var(--accent);text-decoration:underline;text-underline-offset:3px}
code{font-family:var(--f-mono);font-size:.88em;overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:20px;border-radius:var(--r-sm);background:var(--bg-panel-2)}
pre code{overflow-wrap:normal;white-space:pre}
.btn{display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;gap:8px;min-height:50px;padding:10px 26px;border-radius:var(--r-sm);font-size:16px;font-weight:700;white-space:nowrap;transition:transform var(--fast),opacity var(--fast),background-color var(--fast)}
.btn:hover{transform:translateY(-1px)}
.btn svg{width:16px;height:16px}
.btn-primary{min-width:172px;color:var(--white);background:linear-gradient(180deg,var(--accent-2),var(--accent) 70%);box-shadow:inset 0 1px 0 var(--hi-soft),0 0 0 1px var(--accent-dark),0 14px 28px -12px var(--shade-cta)}
.btn-primary:hover{background:var(--accent-dark)}
.btn-ghost,.btn-secondary{min-width:150px;color:var(--accent-dark);background:var(--hi-soft);box-shadow:inset 0 0 0 1.5px var(--accent)}
.btn:active,.btn.is-active{transform:translateY(1px);box-shadow:inset 0 0 0 2px var(--accent-dark)}
.btn:disabled,.btn[aria-disabled="true"]{opacity:.5;cursor:not-allowed;transform:none}
.btn-small{min-height:40px;min-width:0;padding:8px 16px;font-size:14px}
.cta-row{display:flex;justify-content:center;flex-wrap:wrap;gap:12px;margin-bottom:18px}
.topbar{position:relative;z-index:60}
.topbar-in{position:relative;z-index:63;max-width:var(--wrap);margin:0 auto;padding:0 var(--gutter);height:var(--header-h);display:flex;align-items:center;flex-wrap:nowrap;gap:30px;border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:18px;letter-spacing:-.01em;white-space:nowrap;flex-shrink:0}
.brand img{width:32px;height:32px;border-radius:var(--r-mark)}
.brand-word{color:var(--text)}
.brand-word b{color:var(--accent);font-weight:700}
.brand-zh{font-size:14px;font-weight:500;color:var(--text-muted)}
.desktop-nav{flex:1;min-width:0;height:100%}
.tabs{display:flex;align-items:center;list-style:none;margin:0;padding:0;height:100%;gap:2px}
.tabs li{height:100%;min-width:0}
.tab{position:relative;display:flex;align-items:center;height:100%;padding:0 13px;font-size:14.5px;font-weight:500;color:var(--text-muted);white-space:nowrap;transition:color var(--fast)}
.tab::after{content:"";position:absolute;left:13px;right:13px;bottom:-1px;height:3px;border-radius:var(--r-light) var(--r-light) 0 0;background:var(--accent);transform:scaleX(0);opacity:0;transition:transform .25s,opacity .25s}
.tab:hover{color:var(--text)}
.tab:hover::after{transform:scaleX(.35);opacity:.45}
.tab[aria-current="page"]{color:var(--text);font-weight:600}
.tab[aria-current="page"]::after{transform:scaleX(1);opacity:1}
.topbar-end{margin-left:auto;display:flex;align-items:center;gap:10px;flex-shrink:0}
.language{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-width:44px;width:auto;height:36px;padding:0 12px;border-radius:var(--r-pill);font-size:14px;color:var(--text-muted);white-space:nowrap}
.lang span{white-space:nowrap}
.lang:hover{background:var(--hi-soft)}
.lang svg{width:16px;height:16px}
.lang-panel{position:absolute;z-index:80;right:0;top:calc(100% + 10px);width:180px;padding:8px;background:var(--bg-panel);border-radius:var(--r-md);box-shadow:var(--lift-card)}
.lang-panel a{display:flex;align-items:center;min-height:44px;padding:8px 12px;border-radius:var(--r-xs)}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{color:var(--accent);background:var(--accent-soft)}
.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:14px;font-weight:600;white-space:nowrap;box-shadow:inset 0 1px 0 var(--hi-soft),0 8px 18px -10px var(--shade-cta)}
.menu-button{display:none;align-items:center;justify-content:center;flex-direction:column;gap:5px;min-width:44px;min-height:44px;border-radius:var(--r-xs);color:var(--text)}
.menu-line{display:block;width:20px;height:2px;background:currentColor}
.mobile-drawer{display:none;position:fixed;z-index:62;top:var(--header-h);right:0;left:0;height:calc(100dvh - var(--header-h));max-height:calc(100dvh - var(--header-h));overflow-y:auto;overscroll-behavior:contain;padding:16px var(--gutter) 32px;background:var(--bg-panel)}
.mobile-drawer a{display:flex;align-items:center;width:100%;min-height:44px;padding:10px 12px;border-radius:var(--r-xs)}
.mobile-drawer a:hover,.mobile-drawer a[aria-current]{background:var(--accent-soft);color:var(--accent)}
.drawer-languages{margin-top:20px;padding-top:16px;border-top:1px solid var(--border)}
.nav-veil{display:none;position:fixed;z-index:61;inset:var(--header-h) 0 0;background:var(--veil)}
html.nav-open{overflow:hidden}
.site-footer{background:var(--bg-panel-2);border-top:1px solid var(--hi);padding-top:56px;padding-bottom:24px}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:40px}
.footer-grid>*{min-width:0}
.footer-brand p{margin-top:18px;max-width:300px;color:var(--text-muted)}
.footer-title{font-size:14px;font-family:var(--f-body);font-weight:700;margin-bottom:12px}
.footer-links a{display:inline-flex;align-items:center;min-height:32px;padding-block:4px;font-size:14px;color:var(--text-muted)}
.footer-links a:hover{color:var(--accent);text-decoration:underline}
.footer-bottom{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;margin-top:36px;padding-top:20px;border-top:1px solid var(--border);color:var(--text-muted);font-size:13px}
.footer-legal{display:flex;gap:20px;flex-wrap:wrap}
.footer-legal a{display:inline-flex;align-items:center;min-height:28px}
.reveal{transition:opacity var(--reveal-time) var(--ease),transform var(--reveal-time) var(--ease)}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:relative;display:block;min-width:0;max-width:100%;min-height:80px;overflow:hidden;margin-block:24px}
#server-status+*{margin-top:24px}
#server-status :where(.grid,ul){max-width:100%;min-width:0}
.decorated{position:relative;overflow-x:clip}
body:has(.toc-tabs) section[id]{scroll-margin-top:var(--chapter-offset)}
@media(min-width:1101px) and (max-width:1240px){
  .topbar-in{gap:16px}.tab{padding-inline:9px;font-size:13px}.tab::after{left:9px;right:9px}.topbar-end{gap:4px}.lang{padding-inline:8px}
}
@media(max-width:1100px){
  .desktop-nav{display:none}.topbar-in{gap:16px}.topbar-end{margin-left:auto}.menu-button{display:inline-flex}
  .mobile-drawer.is-open,.nav-veil.is-open{display:block}
}
@media(max-width:768px){
  h1{font-size:clamp(28px,6vw,40px)}h2{font-size:30px}
  .section{padding-top:48px;padding-bottom:48px}
  .grid-three{grid-template-columns:1fr}.grid-five{grid-template-columns:repeat(2,minmax(0,1fr))}
  .footer-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:28px}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .tilt,.tilt-card,[data-tilt]{transform:none}
  .decorated{max-width:100%}
  .topbar-in{gap:8px}.brand{gap:6px;font-size:16px}.brand img{width:28px;height:28px}
  .topbar-end{gap:2px;margin-left:auto}.login{padding-inline:12px;font-size:13px}
  .lang{padding-inline:7px;font-size:12px;gap:4px}.lang svg{width:14px;height:14px}
  .brand-zh{display:none}.panel,.card{padding:22px}
  .btn{padding-inline:20px}.btn-primary{min-width:146px}.btn-ghost{min-width:130px}
}
@media(max-width:359px){
  .brand{font-size:14px}.brand img{width:24px;height:24px}.lang{padding-inline:4px;font-size:11px}
  .login{padding-inline:9px}.menu-button{min-width:40px}
  .footer-grid{grid-template-columns:1fr}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}