:root{
  --bg:#E6EEF8;
  --bg-top:#F1F6FD;
  --bg-bottom:#DDE8F6;
  --panel:#F7FAFE;
  --panel-2:#D8E4F3;
  --border:#C5D4E8;
  --border-soft:rgba(197,212,232,.7);
  --accent:#1D63D8;
  --accent-dark:#0E3E96;
  --lagoon:#17B3C6;
  --lagoon-deep:#0E8FA3;
  --coral:#FF6F61;
  --coral-2:#FFA07A;
  --text:#0B1A33;
  --muted:#52627C;
  --success:#1F9D6B;
  --success-soft:rgba(31,157,107,.18);
  --warn:#D98A12;
  --error:#D2404A;
  --white:#FFFFFF;
  --transparent:transparent;
  --tide-soft:#EAF2FD;
  --tide-line:#BCD3F3;
  --select:#E2EDFD;
  --card-edge:#0A2C6E;
  --on-dark-muted:rgba(255,255,255,.74);
  --glow-lagoon:rgba(23,179,198,.30);
  --glow-tide:rgba(112,164,240,.36);
  --glow-card:rgba(23,179,198,.34);
  --glass:rgba(255,255,255,.62);
  --glass-edge:rgba(255,255,255,.85);
  --hl-white:rgba(255,255,255,.92);
  --hl-white-soft:rgba(255,255,255,.34);
  --shadow-accent-12:rgba(29,99,216,.12);
  --shadow-accent-14:rgba(29,99,216,.14);
  --shadow-accent-24:rgba(29,99,216,.24);
  --shadow-deep:rgba(14,62,150,.24);
  --shadow-ink:rgba(11,26,51,.16);
  --shadow-ink-soft:rgba(11,26,51,.08);
  --shadow-ink-cta:rgba(11,26,51,.28);
  --shadow-coral:rgba(255,111,97,.32);
  --veil:rgba(11,26,51,.36);
  --flag-red:#D7263D;
  --flag-blue:#2A3D8F;
  --flag-black:#1C1C1C;
  --flag-gold:#F5C400;
  --flag-rim:rgba(11,26,51,.14);
  --sky-top:#A9CDF3;
  --sky-low:#EAF3FD;
  --sea-far:#3F8EDD;
  --sea-mid:#33B1CB;
  --sea-near:#8FD8E2;
  --sand:#F4E9D4;
  --sand-2:#E8D6B4;
  --foam:rgba(255,255,255,.88);
  --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-basin:36px;
  --r-card:28px;
  --r-canvas:32px;
  --r-win:16px;
  --r-lg:18px;
  --r-md:14px;
  --r-sm:10px;
  --r-xs:7px;
  --r-icon:11px;
  --r-pill:999px;
  --r-round:50%;
  --gutter:32px;
  --wrap:1200px;
  --header-height:76px;
  --anchor-gap:96px;
  --toc-offset:16px;
  --toc-landing:100px;
  --body-size:16px;
  --small-size:14px;
  --h1-size:clamp(52px,5vw,68px);
  --h2-size:clamp(28px,3vw,40px);
  --h3-size:22px;
  --weight-normal:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --weight-heavy:800;
  --weight-display:900;
  --panel-shadow:inset 0 1px 0 var(--hl-white),0 24px 56px -20px var(--shadow-accent-12);
  --ease:cubic-bezier(.2,.7,.2,1);
  --fast:.18s;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:var(--anchor-gap)}
html.nav-open{overflow:hidden}
body{margin:0;padding:0;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--body-size);line-height:1.6;-webkit-font-smoothing:antialiased}
h1,h2,h3,h4,p,figure,blockquote{margin:0}
h1,h2,h3,h4{font-family:var(--font-display);text-wrap:balance;overflow-wrap:break-word}
h1{font-size:var(--h1-size);line-height:1.12;font-weight:var(--weight-display);letter-spacing:-.02em}
h2{font-size:var(--h2-size);line-height:1.25;font-weight:var(--weight-heavy);letter-spacing:-.02em}
h3{font-size:var(--h3-size);line-height:1.4;font-weight:var(--weight-bold)}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit}
button{cursor:pointer}
button{border:0;color:inherit;background:var(--transparent)}
button,summary,a,input,select,textarea{-webkit-tap-highlight-color:var(--success-soft)}
:where(a,button,summary,input,select,textarea,[tabindex]):focus-visible{outline:2px solid var(--accent);outline-offset:3px}
button:disabled,.btn[aria-disabled="true"]{cursor:not-allowed;opacity:.55}
img{display:block;max-width:100%;height:auto}
svg{display:block;flex-shrink:0}
ul,ol{padding-left:1.5em}
pre{max-width:100%;overflow-x:auto;background:var(--panel-2);padding:20px;border-radius:var(--r-md);font-family:var(--font-mono)}
code{font-family:var(--font-mono);overflow-wrap:anywhere}
pre code{overflow-wrap:normal}
hr{border:0;border-top:1px solid var(--border);margin:32px 0}
[hidden]{display:none!important}
.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);clip-path:inset(50%);white-space:nowrap;border:0;padding:0;margin:-1px}
.no-break{white-space:nowrap}
.icon-defs{position:absolute;width:0;height:0;overflow:hidden}
.wrap{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gutter)}
.sec{padding-top:64px;padding-bottom:64px}
.stack>*+*{margin-top:20px}
.grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}
.grid>*,.split>*,.wrap>*,.nav>*{min-width:0}
.split{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:32px}
.muted{color:var(--muted)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.kicker{font-size:var(--small-size);font-weight:var(--weight-bold);color:var(--accent-dark)}
.kw{background:linear-gradient(90deg,var(--accent),var(--lagoon-deep));-webkit-background-clip:text;background-clip:text;color:var(--transparent);-webkit-box-decoration-break:clone;box-decoration-break:clone}
.panel{padding:28px;background:var(--panel);border-radius:var(--r-card);box-shadow:var(--panel-shadow)}
.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:24px;margin-bottom:28px}
.section-head>div{min-width:0}
.section-head p{margin-top:12px;color:var(--muted)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:48px;padding:10px 26px;border-radius:var(--r-md);font-size:16px;font-weight:var(--weight-bold);letter-spacing:.01em;flex-shrink:0;white-space:nowrap;transition:background-color var(--fast),box-shadow var(--fast)}
.btn svg{width:16px;height:16px}
.btn-primary{background:var(--text);color:var(--white);box-shadow:inset 0 1px 0 var(--hl-white-soft),0 14px 28px -12px var(--shadow-ink-cta)}
.btn-primary:hover{background:var(--accent-dark)}
.btn-primary:active{background:var(--accent)}
.btn-ghost,.btn-secondary{background:var(--tide-soft);color:var(--accent-dark);box-shadow:inset 0 0 0 1px var(--tide-line)}
.btn-ghost:hover,.btn-secondary:hover{background:var(--white)}
.btn-accent{background:var(--accent);color:var(--white);box-shadow:0 14px 28px -12px var(--shadow-accent-24)}
.btn-accent:hover{background:var(--accent-dark)}
.btn-small{min-height:36px;padding:6px 16px;font-size:14px}
.btn-row{display:flex;align-items:center;flex-wrap:wrap;gap:12px}
.badge,.tag{display:inline-flex;align-items:center;gap:8px;min-height:26px;max-width:100%;padding:3px 12px;border-radius:var(--r-pill);background:var(--glass);box-shadow:inset 0 0 0 1px var(--glass-edge),0 6px 16px -10px var(--shadow-accent-24);font-size:13px;font-weight:var(--weight-semibold);color:var(--accent-dark);overflow-wrap:anywhere}
.tag{background:var(--tide-soft);box-shadow:none}
.status-dot{width:8px;height:8px;background:var(--success);border-radius:var(--r-round);flex-shrink:0}
.icon-box{width:40px;height:40px;border-radius:var(--r-icon);display:grid;place-items:center;background:linear-gradient(135deg,var(--accent),var(--lagoon));color:var(--white);flex-shrink:0;overflow:hidden}
.icon-box svg{width:22px;height:22px}
.reveal{transition:opacity .35s ease,transform .35s 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:120px;overflow:hidden;margin-block:24px}
#server-status+*{margin-top:32px}
.prose{max-width:820px}
.prose p,.prose ul,.prose ol{margin-block:18px}
.prose h2{margin-top:48px;margin-bottom:20px}
.prose h3{margin-top:28px;margin-bottom:14px}
.prose a:not(.btn){color:var(--accent-dark);text-decoration:underline;text-underline-offset:3px}
.prose li+li{margin-top:8px}
.prose section[id]{margin-top:40px}

/* Shared header: the fixed drawer is not inside a filtered ancestor. */
#site-header{position:relative;z-index:100;min-height:var(--header-height)}
.nav{position:relative;z-index:104;height:60px;display:flex;align-items:center;gap:28px;padding:0 24px 0 28px;flex-wrap:nowrap}
#site-header>.nav{height:var(--header-height);background:var(--bg-top)}
.brand{display:flex;align-items:center;gap:10px;flex:none;min-height:44px}
.brand-mark{width:34px;height:34px;flex:none}
.brand-en{font-family:var(--font-display);font-weight:var(--weight-heavy);font-size:19px;letter-spacing:-.02em;color:var(--text);white-space:nowrap}
.brand-zh{font-size:14px;font-weight:var(--weight-medium);color:var(--muted)}
.nav-main{display:flex;align-items:center;gap:4px;margin-left:12px;flex:1;min-width:0}
.nav-list{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:4px}
.nav-link{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:36px;padding:6px 13px;border-radius:var(--r-sm);font-size:15px;font-weight:var(--weight-semibold);color:var(--text);white-space:nowrap}
.nav-link:hover{color:var(--accent)}
.nav-link[aria-current="page"],.drop-panel a[aria-current="page"]{background:var(--glass);box-shadow:inset 0 0 0 1px var(--glass-edge)}
.drop{position:relative}
.drop:not([open])>.drop-panel{display:none}
.drop[open]>.drop-panel{display:block}
.drop summary{list-style:none;cursor:pointer}
.drop summary::-webkit-details-marker{display:none}
.caret{width:12px;height:12px;color:var(--muted)}
.drop-panel,.lang-panel{position:absolute;top:44px;left:0;z-index:110;min-width:200px;padding:8px;border-radius:var(--r-md);background:var(--panel);box-shadow:0 18px 40px -12px var(--shadow-accent-24),inset 0 0 0 1px var(--border-soft)}
.drop-panel a,.lang-panel a{display:flex;align-items:center;min-height:40px;padding:9px 12px;border-radius:var(--r-xs);font-size:14px;font-weight:var(--weight-semibold)}
.drop-panel a:hover,.lang-panel a:hover{background:var(--tide-soft);color:var(--accent-dark)}
.drop-note{display:block;font-size:12px;font-weight:var(--weight-medium);color:var(--muted)}
.nav-side{margin-left:auto;display:flex;align-items:center;gap:10px;flex-shrink:0}
.lang{position:relative}
.lang-button,.lang summary{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:36px;width:auto;padding:6px 12px;border-radius:var(--r-sm);font-size:14px;font-weight:var(--weight-semibold);white-space:nowrap}
.lang-button svg,.lang summary svg{width:16px;height:16px;color:var(--accent-dark)}
.lang-name{white-space:nowrap}
.lang-panel{left:auto;right:0;min-width:150px}
.lang-panel a[aria-current="true"]{background:var(--tide-soft);color:var(--accent-dark)}
.btn-login{display:inline-flex;align-items:center;justify-content:center;min-height:38px;padding:6px 20px;border-radius:var(--r-md);background:var(--accent);color:var(--white);font-size:15px;font-weight:var(--weight-bold);white-space:nowrap;box-shadow:inset 0 1px 0 var(--hl-white-soft),0 10px 22px -10px var(--shadow-accent-24)}
.btn-login:hover{background:var(--accent-dark)}
.nav-menu{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;border-radius:var(--r-sm);color:var(--text)}
.menu-line{display:block;width:20px;height:2px;background:currentColor}
.nav-drawer{position:fixed;top:var(--header-height);left:0;right:0;z-index:103;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}
.nav-drawer a{display:flex;align-items:center;width:100%;min-height:48px;padding:12px 16px;border-radius:var(--r-sm);font-weight:var(--weight-semibold)}
.nav-drawer a:hover,.nav-drawer a[aria-current="page"]{background:var(--tide-soft);color:var(--accent-dark)}
.drawer-label{margin:18px 16px 8px;color:var(--muted);font-size:13px;font-weight:var(--weight-bold)}
.nav-veil{position:fixed;inset:var(--header-height) 0 0;z-index:102;background:var(--veil)}
.site-footer{margin-top:48px;padding-top:48px;padding-bottom:28px;background:var(--panel-2);box-shadow:inset 0 1px 0 var(--hl-white)}
.footer-grid{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:40px}
.footer-brand p{margin-top:16px;max-width:360px;color:var(--muted);font-size:14px}
.footer-heading{font-size:15px;font-weight:var(--weight-bold);margin-bottom:12px}
.footer-links{list-style:none;margin:0;padding:0;display:grid;gap:4px}
.footer-links a{display:inline-flex;align-items:center;min-height:30px;padding-block:3px;font-size:14px;color:var(--muted)}
.footer-links a:hover{color:var(--accent-dark);text-decoration:underline}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 20px;margin-top:32px}
.footer-languages a{display:inline-flex;align-items:center;min-height:30px;font-size:14px;color:var(--accent-dark)}
.footer-bottom{display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px 24px;border-top:1px solid var(--border);margin-top:24px;padding-top:20px;font-size:13px;color:var(--muted)}
.footer-legal{display:flex;gap:20px}
.footer-legal a{display:inline-flex;align-items:center;min-height:24px}
@media(min-width:1025px){
  .nav-drawer,.nav-veil{display:none!important}
}
@media(max-width:1100px){
  .nav{gap:14px;padding-inline:20px}
  .nav-link{padding-inline:9px;font-size:14px}
  .nav-main{margin-left:0}
}
@media(max-width:1024px){
  .nav-main{display:none}
  .nav-menu{display:flex}
  .nav-side{margin-left:auto;gap:6px}
  .footer-grid{grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:1/-1}
}
@media(max-width:768px){
  :root{--gutter:24px;--h1-size:clamp(28px,6.5vw,40px)}
  .grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .split{grid-template-columns:minmax(0,1fr)}
  .section-head{align-items:flex-start;flex-wrap:wrap}
  .sec{padding-top:44px;padding-bottom:44px}
}
@media(max-width:640px){
  :root{--gutter:16px;--header-height:64px;--anchor-gap:80px}
  .no-break{white-space:normal}
  .tilt,[data-tilt]{transform:none}
  .nav{height:var(--header-height);gap:8px;padding-inline:12px}
  .brand{gap:7px}
  .brand-mark{width:28px;height:28px}
  .brand-en{font-size:16px}
  .nav-side{margin-left:auto;gap:2px}
  .lang-button,.lang summary{padding-inline:6px;font-size:12px;gap:4px}
  .lang-button svg{width:14px;height:14px}
  .btn-login{padding-inline:12px;font-size:13px}
  .nav-menu{min-width:44px;min-height:44px}
  .grid{grid-template-columns:minmax(0,1fr)}
  .panel{padding:22px}
  .footer-grid{grid-template-columns:minmax(0,1fr);gap:28px}
  .footer-brand{grid-column:auto}
  .footer-bottom{flex-direction:column}
  .prose{overflow-wrap:break-word}
}
@media(max-width:359px){
  .brand-en{font-size:14px}
  .brand-mark{width:24px;height:24px}
  .nav{padding-inline:8px;gap:4px}
  .lang-button,.lang summary{font-size:11px;padding-inline:4px}
  .lang-button svg{display:none}
  .btn-login{padding-inline:9px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}