:root {
  --bg:#E7ECF6;
  --bg-top:#EFF3FA;
  --bg-bottom:#E2E8F4;
  --panel:#F6F8FD;
  --panel-2:#DCE3F1;
  --side:#EBEFF8;
  --white:#FFFFFF;
  --border:#CCD5E6;
  --border-soft:#DDE3EF;
  --accent:#C9521F;
  --accent-dark:#9E3C14;
  --accent-2:#F08A4B;
  --accent-wash:rgba(201,82,31,.09);
  --accent-shadow:rgba(201,82,31,.10);
  --accent-glow:rgba(201,82,31,.06);
  --accent-btn-shadow:rgba(201,82,31,.32);
  --accent-2-haze:rgba(240,138,75,.55);
  --text:#18213A;
  --text-muted:#5A6680;
  --text-faint:#8A94AA;
  --success:#1E8F5A;
  --success-wash:rgba(30,143,90,.14);
  --warn:#B9800F;
  --error:#C23B3B;
  --ink-frame:#1E2438;
  --ink-frame-2:#151A2A;
  --ink-summary:#1B2238;
  --ink-cam:#2C3450;
  --ink-edge:rgba(9,12,22,.55);
  --hi-line:rgba(255,255,255,.92);
  --hi-line-dim:rgba(255,255,255,.14);
  --hi-line-faint:rgba(255,255,255,.10);
  --shade-cool:rgba(40,56,92,.30);
  --shade-deep:rgba(24,33,58,.34);
  --shade-ink:rgba(24,33,58,.08);
  --shade-ink-2:rgba(24,33,58,.14);
  --veil:rgba(24,33,58,.34);
  --wall-top:#C9D6EE;
  --wall-mid:#DCDDEB;
  --wall-horizon:#F3C3A0;
  --ridge-1:#B4C0D9;
  --ridge-2:#99A8C7;
  --ridge-3:#8292B3;
  --tl-red:#E0605A;
  --tl-amber:#E3B04B;
  --tl-green:#58B56E;
  --chip-blue-bg:#DCE7FA;
  --chip-blue-ink:#2F5DA8;
  --chip-violet-bg:#E7E1F7;
  --chip-violet-ink:#5B48A3;
  --chip-amber-bg:#F5E7C6;
  --chip-amber-ink:#87600F;
  --chip-green-bg:#D9EFE3;
  --chip-green-ink:#1E7A50;
  --chip-rose-bg:#F5DFE3;
  --chip-rose-ink:#943D54;
  --chip-edge:rgba(24,33,58,.06);
  --flag-red:#C8323C;
  --flag-blue:#2B3A6B;
  --flag-white:#FFFFFF;
  --flag-edge:rgba(24,33,58,.14);
  --transparent:transparent;
  --font-display:Georgia,"Times New Roman","Source Han Serif SC","Noto Serif SC","Songti SC",STSong,"SimSun",serif;
  --font-body:Inter,"Noto Sans SC","PingFang SC","Hiragino Sans","Microsoft YaHei","Apple SD Gothic Neo","Malgun Gothic",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SF Mono",Menlo,Consolas,monospace;
  --r-xs:6px;
  --r-sm:8px;
  --r-md:10px;
  --r-lg:12px;
  --r-xl:24px;
  --r-panel:28px;
  --r-pill:999px;
  --r-circle:50%;
  --r-flag:3px;
  --r-slot:7px;
  --r-icon:5px;
  --r-note:14px;
  --r-mobile:16px;
  --gutter:24px;
  --content-width:1200px;
  --reading-width:800px;
  --header-height:64px;
  --anchor-offset:88px;
  --toc-offset:140px;
  --shadow-panel:0 0 0 1px var(--border-soft),inset 0 1px 0 var(--hi-line),0 36px 80px -30px var(--accent-shadow);
  --shadow-small:0 0 0 1px var(--border-soft),inset 0 1px 0 var(--hi-line),0 8px 18px -12px var(--shade-cool);
  --duration-fast:.18s;
  --duration-reveal:.35s;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:var(--anchor-offset);scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:16px;line-height:1.6;-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;vertical-align:middle}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;padding:0;cursor:pointer}
button:disabled{cursor:not-allowed}
[hidden]{display:none!important}
h1,h2,h3,h4,p,blockquote,figure{margin-top:0}
h1,h2,h3{overflow-wrap:break-word;text-wrap:balance}
h1{font-family:var(--font-display);font-size:clamp(52px,5vw,68px);font-weight:500;line-height:1.12;letter-spacing:-.02em}
h2{font-family:var(--font-display);font-size:40px;font-weight:500;line-height:1.2;letter-spacing:-.02em}
h3{font-size:22px;line-height:1.4;font-weight:600}
p{margin-bottom:1.2em}
ul,ol{padding-left:1.5em}
button,a,summary,[tabindex],input,select,textarea{-webkit-tap-highlight-color:var(--transparent)}
:where(a,button,summary,[tabindex],input,select,textarea):focus-visible{outline:2px solid var(--text);outline-offset:3px;border-radius:var(--r-sm)}
code{font-family:var(--font-mono);overflow-wrap:anywhere;font-size:.9em}
pre{max-width:100%;min-width:0;overflow-x:auto;padding:20px;border-radius:var(--r-md);background:var(--ink-frame);color:var(--panel)}
pre code{overflow-wrap:normal;white-space:pre}
hr{border:0;border-top:1px solid var(--border);margin-block:32px}
.wrap{width:100%;max-width:calc(var(--content-width) + var(--gutter)*2);margin-inline:auto;padding-inline:var(--gutter)}
.reading-wrap{width:100%;max-width:calc(var(--reading-width) + var(--gutter)*2);margin-inline:auto;padding-inline:var(--gutter)}
.sec{padding-top:64px;padding-bottom:64px}
.section-head{margin-bottom:32px;max-width:800px}
.section-head p{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))}
.stack{display:flex;flex-direction:column;gap:20px;min-width:0}
.row{display:flex;align-items:center;flex-wrap:wrap;gap:12px}
.muted{color:var(--text-muted)}
.num{font-family:var(--font-mono);font-feature-settings:"tnum" 1;font-variant-numeric:tabular-nums;letter-spacing:-.01em}
.no-break{white-space:nowrap}
.display-text{font-family:var(--font-display);font-weight:500}
.prose{min-width:0;overflow-wrap:break-word}
.prose h2{margin-top:48px;font-size:32px}
.prose h3{margin-top:32px}
.prose a:not(.btn){text-decoration:underline;text-underline-offset:3px}
.prose li{margin-block:8px}
.prose img{border-radius:var(--r-lg)}
.prose blockquote{margin-inline:0;padding:20px 24px;border-left:3px solid var(--border);background:var(--panel)}
.skip{position:absolute;left:16px;top:-80px;z-index:100;padding:8px 14px;border-radius:var(--r-sm);background:var(--text);color:var(--white);font-size:14px}
.skip:focus{top:12px}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
.btn{display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;gap:8px;min-height:48px;padding:10px 26px;border-radius:var(--r-md);font-size:16px;font-weight:600;white-space:nowrap;text-align:center}
.btn svg{width:16px;height:16px}
.btn-primary{color:var(--white);background:linear-gradient(100deg,var(--accent) 0%,var(--accent) 38%,var(--accent-2) 135%);box-shadow:inset 0 1px 0 var(--hi-line-dim),0 0 0 1px var(--accent-dark),0 14px 28px -12px var(--accent-btn-shadow)}
.btn-primary:hover,.btn-primary.is-hover{background:var(--accent-dark)}
.btn-primary:active{transform:translateY(1px)}
.btn-ghost{color:var(--text);background:var(--panel);box-shadow:0 0 0 1px var(--border),inset 0 1px 0 var(--hi-line),0 6px 14px -10px var(--shade-cool)}
.btn-ghost:hover{background:var(--white)}
.btn:disabled,.btn[aria-disabled="true"]{background:var(--panel-2);color:var(--text-muted);box-shadow:inset 0 0 0 1px var(--border)}
.btn.is-focus{outline:2px solid var(--text);outline-offset:3px}
.text-link{display:inline-flex;align-items:center;min-height:24px;text-decoration:underline;text-underline-offset:4px}
.panel{padding:32px;border-radius:var(--r-xl);background:var(--panel);box-shadow:var(--shadow-panel);min-width:0}
.surface-card{padding:24px;border-radius:var(--r-lg);background:var(--panel);box-shadow:var(--shadow-small);min-width:0}
.badge,.chip{display:inline-flex;align-items:center;gap:6px;min-height:24px;max-width:100%;padding:3px 10px;border-radius:var(--r-pill);font-size:12px;font-weight:500;overflow:hidden;overflow-wrap:anywhere;background:var(--panel-2);color:var(--text)}
.chip-blue{background:var(--chip-blue-bg);color:var(--chip-blue-ink)}
.chip-violet{background:var(--chip-violet-bg);color:var(--chip-violet-ink)}
.chip-amber{background:var(--chip-amber-bg);color:var(--chip-amber-ink)}
.chip-green{background:var(--chip-green-bg);color:var(--chip-green-ink)}
.chip-rose{background:var(--chip-rose-bg);color:var(--chip-rose-ink)}
.dot{display:block;width:8px;height:8px;flex-shrink:0;border-radius:var(--r-circle);background:var(--accent)}
.topbar,#site-header{position:relative;z-index:40;background:var(--bg-top)}
.topbar{border-bottom:1px solid var(--border-soft)}
.topbar-in{width:min(1200px,calc(100% - 48px));margin-inline:auto;height:var(--header-height);display:flex;align-items:center;gap:36px;flex-wrap:nowrap}
.brand{display:inline-flex;align-items:center;gap:10px;flex-shrink:0;min-height:36px}
.brand-mark{display:block;width:30px;height:30px;flex-shrink:0}
.brand-en{font-weight:700;font-size:18px;letter-spacing:-.015em;color:var(--text)}
.brand-zh{font-size:14px;font-weight:400;color:var(--text-muted)}
.mainnav{display:flex;align-items:center;flex:1;min-width:0}
.mainnav ul{display:flex;align-items:center;gap:2px;list-style:none;margin:0;padding:0}
.mainnav a,.more-btn{display:inline-flex;align-items:center;gap:4px;height:36px;padding:0 12px;border-radius:var(--r-sm);font-size:14.5px;color:var(--text-muted);white-space:nowrap}
.mainnav a:hover,.more-btn:hover{color:var(--text);background:var(--panel)}
.mainnav a[aria-current="page"],.more-btn.is-current{color:var(--text);font-weight:600}
.nav-more{position:relative}
.nav-more summary{list-style:none;cursor:pointer}
.nav-more summary::-webkit-details-marker{display:none}
.more-btn svg{width:12px;height:12px}
.nav-drop{position:absolute;z-index:55;top:calc(100% + 4px);left:0;min-width:168px;padding:6px;background:var(--panel);border-radius:var(--r-md);box-shadow:0 0 0 1px var(--border-soft),0 18px 36px -16px var(--shade-cool),inset 0 1px 0 var(--hi-line)}
.nav-drop a{display:flex;width:100%;height:36px;font-size:14px}
.topbar-end{display:flex;align-items:center;gap:10px;flex-shrink:0;margin-left:auto}
.lang-switch{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;height:36px;min-width:44px;width:auto;padding:0 12px;border-radius:var(--r-sm);font-size:14px;color:var(--text-muted);white-space:nowrap}
.lang span{white-space:nowrap}
.lang:hover{background:var(--panel);color:var(--text)}
.lang svg{width:15px;height:15px}
.lang .chev{width:11px;height:11px}
.lang-panel{position:absolute;right:0;top:calc(100% + 8px);z-index:70;min-width:170px;padding:6px;background:var(--panel);border-radius:var(--r-md);box-shadow:var(--shadow-small)}
.lang-panel a{display:flex;align-items:center;min-height:40px;padding:8px 12px;border-radius:var(--r-xs);font-size:14px}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--panel-2)}
.btn-login{display:inline-flex;align-items:center;justify-content:center;min-height:36px;padding:6px 18px;border-radius:var(--r-sm);background:var(--text);color:var(--white);font-size:14px;font-weight:600;white-space:nowrap;box-shadow:inset 0 1px 0 var(--hi-line-dim),0 6px 14px -8px var(--shade-deep)}
.btn-login:hover{background:var(--ink-frame)}
.menu-toggle{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;border-radius:var(--r-sm)}
.menu-line{display:block;width:20px;height:2px;background:currentColor}
.menu-toggle[aria-expanded="true"]{background:var(--panel-2)}
.mobile-drawer{position:fixed;z-index:38;top:var(--header-height);right:0;left:0;height:calc(100dvh - var(--header-height));max-height:calc(100dvh - var(--header-height));padding:16px var(--gutter) 32px;background:var(--panel);overflow-y:auto;overscroll-behavior:contain}
.mobile-drawer a{display:flex;align-items:center;width:100%;min-height:44px;padding:10px 14px;border-radius:var(--r-sm)}
.mobile-drawer a:hover,.mobile-drawer a[aria-current="page"]{background:var(--panel-2)}
.drawer-label{padding:20px 14px 8px;margin:0;font-size:12px;color:var(--text-muted);border-top:1px solid var(--border-soft)}
.menu-veil{position:fixed;z-index:37;inset:var(--header-height) 0 0;background:var(--veil)}
html.nav-open{overflow:hidden}
.site-footer{padding-top:56px;padding-bottom:24px;background:var(--panel-2);border-top:1px solid var(--border)}
.footer-grid{display:grid;grid-template-columns:1.2fr 1fr 1fr;gap:48px}
.footer-grid>*{min-width:0}
.footer-brand p{max-width:360px;margin-top:16px;color:var(--text-muted);font-size:14px}
.footer-title{font-family:var(--font-body);font-size:14px;font-weight:600;margin:0 0 16px}
.footer-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 16px}
.footer-links a,.footer-languages a,.legal-links a{display:inline-flex;align-items:center;min-height:28px;font-size:13px;color:var(--text-muted)}
.footer-links a:hover,.footer-languages a:hover,.legal-links a:hover{color:var(--text);text-decoration:underline;text-underline-offset:3px}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 20px;margin-top:32px;padding-top:20px;border-top:1px solid var(--border)}
.footer-bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px;margin-top:20px;font-size:12px;color:var(--text-muted)}
.legal-links{display:flex;flex-wrap:wrap;gap:12px}
.reveal{transition:opacity var(--duration-reveal) ease,transform var(--duration-reveal) ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:relative;display:block;min-height:64px;width:100%;max-width:100%;min-width:0;overflow:hidden;margin-block:24px}
#server-status+*{margin-top:24px}
.decor-section{position:relative;overflow-x:clip}
.decor-halo{position:absolute;inset:24% 0 0 44%;max-width:100%;pointer-events:none;background:radial-gradient(closest-side,var(--accent-glow),var(--transparent))}
@media(min-width:901px){
  .mobile-drawer,.menu-veil{display:none}
}
@media(max-width:1100px){
  .topbar-in{gap:24px}
  .mainnav a,.more-btn{padding-inline:9px}
  .brand-zh{display:none}
}
@media(max-width:900px){
  .mainnav{display:none}
  .topbar-end{margin-left:auto}
  .menu-toggle{display:inline-flex}
  .footer-grid{gap:28px;grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:1/-1}
}
@media(max-width:768px){
  :root{--gutter:16px}
  h1{font-size:38px}
  h2{font-size:28px}
  h3{font-size:20px}
  .sec{padding-top:40px;padding-bottom:40px}
  .topbar-in{width:calc(100% - 32px);gap:12px}
  .topbar-end{gap:4px}
  .lang{padding-inline:8px}
  .lang>span{display:none}
  .btn{min-height:46px;padding-inline:22px}
  .grid-three{grid-template-columns:1fr}
  .grid-five{grid-template-columns:repeat(2,minmax(0,1fr))}
  .panel{padding:24px}
}
@media(max-width:640px){
  .no-break{white-space:normal}
  .tilt{transform:none}
  .decor-halo{max-width:100%}
  .footer-grid{grid-template-columns:1fr}
  .footer-brand{grid-column:auto}
  .prose h2{font-size:27px}
}
@media(max-width:360px){
  .brand{gap:7px}
  .brand-en{font-size:16px}
  .brand-mark{width:26px;height:26px}
  .btn-login{padding-inline:12px}
  .topbar-in{gap:6px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none!important;transition:none!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}