:root {
  color-scheme: light;
  --bg:#E6ECF6;
  --bg-top:#F1F5FB;
  --bg-bottom:#DFE7F3;
  --panel:#F6F9FD;
  --panel-2:#D9E1EF;
  --border:#C6D1E3;
  --accent:#86E62C;
  --accent-hi:#D8FF8A;
  --accent-dark:#2E7A12;
  --accent-mid:color-mix(in oklab,var(--accent) 52%,var(--accent-dark));
  --text:#121A2B;
  --text-muted:#56627A;
  --text-faint:#8A95AA;
  --success:#1E9E5A;
  --warn:#C98A0E;
  --error:#D6443A;
  --white:#FFFFFF;
  --clear:transparent;
  --cube-front-a:rgba(201,255,134,.72);
  --cube-front-b:rgba(111,214,38,.72);
  --cube-top:#F9FFEC;
  --cube-side-a:rgba(166,238,78,.9);
  --cube-side-b:rgba(238,255,156,.95);
  --glass-panel:rgba(246,249,253,.82);
  --glass-nav:rgba(246,249,253,.72);
  --spot-core:rgba(246,255,222,.96);
  --spot-mid:rgba(216,255,138,.78);
  --spot-out:rgba(216,255,138,0);
  --lime-30:rgba(134,230,44,.30);
  --lime-24:rgba(134,230,44,.24);
  --lime-14:rgba(134,230,44,.14);
  --lime-10:rgba(134,230,44,.10);
  --leaf-22:rgba(46,122,18,.22);
  --leaf-16:rgba(46,122,18,.16);
  --cool-18:rgba(38,54,90,.18);
  --cool-10:rgba(38,54,90,.10);
  --cool-06:rgba(38,54,90,.06);
  --hi-white:rgba(255,255,255,.72);
  --hi-white-strong:rgba(255,255,255,.96);
  --hi-white-soft:rgba(255,255,255,.38);
  --hi-white-faint:rgba(255,255,255,.16);
  --ink-12:rgba(18,26,43,.12);
  --veil:rgba(18,26,43,.32);
  --flag-red:#D7263D;
  --flag-white:#FFFFFF;
  --flag-navy:#22377A;
  --flag-blue:#2450A6;
  --flag-black:#1C1C20;
  --flag-gold:#F2C230;
  --font-display:"Inter","Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --r-pill:999px;
  --r-lg:18px;
  --r-md:14px;
  --r-sm:10px;
  --r-xs:4px;
  --r-round:50%;
  --gutter:24px;
  --site-width:1248px;
  --reading-width:800px;
  --header-bottom:112px;
  --anchor-offset:96px;
  --toc-offset:16px;
  --text-xs:12px;
  --text-sm:14px;
  --text-base:16px;
  --text-lead:20px;
  --text-h3:24px;
  --text-h2:36px;
  --text-h1:68px;
  --weight-regular:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --shadow-panel:inset 0 1px 0 var(--hi-white-strong),0 18px 44px var(--lime-10);
  --shadow-neutral:inset 0 1px 0 var(--hi-white-strong),0 10px 28px var(--cool-06);
  --ease:cubic-bezier(.2,.7,.2,1);
  --grain:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix values='0 0 0 0 .32 0 0 0 0 .37 0 0 0 0 .5 0 0 0 1.4 -.35'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:var(--anchor-offset)}
html,body{margin:0;min-width:0}
body{background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--text-base);line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
img,video{display:block;max-width:100%;height:auto}
svg{flex-shrink:0;vertical-align:middle}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
a{color:inherit;text-underline-offset:3px}
button,a,input,summary,select,textarea{-webkit-tap-highlight-color:var(--ink-12)}
:focus-visible{outline:2px solid var(--accent-dark);outline-offset:3px;border-radius:var(--r-sm)}
[hidden]{display:none!important}
h1,h2,h3,h4{font-family:var(--font-display);color:var(--text);text-wrap:balance;overflow-wrap:break-word}
h1{margin:14px 0 0;font-weight:var(--weight-bold);font-size:var(--text-h1);line-height:1.1;letter-spacing:-.02em}
h2{font-size:var(--text-h2);line-height:1.22;letter-spacing:-.02em;margin:0 0 24px}
h3{font-size:var(--text-h3);line-height:1.35;margin:0 0 16px}
p{margin:0 0 20px}
ul,ol{padding-left:24px}
li+li{margin-top:6px}
hr{border:0;border-top:1px solid var(--border);margin-block:32px}
code,kbd,pre{font-family:var(--font-mono)}
code{overflow-wrap:anywhere;font-size:.9em}
pre{max-width:100%;overflow-x:auto;padding:20px;background:var(--panel-2);border-radius:var(--r-md)}
pre code{overflow-wrap:normal;white-space:pre}
table{border-collapse:collapse}
.no-break{white-space:nowrap}
.wrap{width:100%;max-width:var(--site-width);margin-inline:auto;padding-inline:var(--gutter);min-width:0}
.reading-wrap{width:100%;max-width:var(--reading-width);margin-inline:auto;padding-inline:var(--gutter);min-width:0}
.sec{padding-top:88px;padding-bottom:88px}
.section-head{max-width:760px;margin-bottom:40px}
.section-head p,.muted{color:var(--text-muted)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.stack{display:grid;gap:24px;min-width:0}
.grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}
.grid>*{min-width:0}
.panel,.card{min-width:0;padding:32px;border:1px solid var(--hi-white-strong);border-radius:var(--r-lg);background:var(--panel);box-shadow:var(--shadow-panel)}
.panel-inset{background:var(--panel-2);padding:24px;border-radius:var(--r-md)}
.prose{min-width:0;overflow-wrap:break-word}
.prose p,.prose li{line-height:1.85}
.prose h2{margin-top:56px}
.prose h3{margin-top:32px}
.prose a{font-weight:var(--weight-medium)}
.prose> :first-child{margin-top:0}
.skip{position:absolute;left:-9999px;top:8px;z-index:100;background:var(--text);color:var(--panel);padding:8px 14px;border-radius:var(--r-pill);text-decoration:none;font-size:var(--text-sm)}
.skip:focus{left:16px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:12px;min-height:48px;padding:10px 26px;border:0;border-radius:var(--r-pill);font-size:var(--text-base);font-weight:var(--weight-semibold);line-height:1.4;text-decoration:none;white-space:nowrap;flex-shrink:0;transition:transform .25s ease,box-shadow .25s ease,background .2s ease}
.btn-primary{padding:8px 8px 8px 26px;background:var(--accent);color:var(--text);box-shadow:inset 0 1px 0 var(--hi-white),0 12px 30px var(--lime-30),0 2px 6px var(--leaf-16)}
.btn-primary .arr{display:grid;place-items:center;width:32px;height:32px;border-radius:var(--r-round);background:var(--text);color:var(--accent)}
.btn-ghost,.btn-secondary{background:var(--clear);color:var(--text);border:1.5px solid var(--text)}
.btn-ink{background:var(--text);color:var(--panel);box-shadow:inset 0 1px 0 var(--hi-white-faint)}
.btn-small{min-height:36px;padding:7px 18px;font-size:var(--text-sm)}
.btn:hover,.btn.is-hover{transform:translateY(-1px);box-shadow:0 10px 24px var(--cool-10)}
.btn:active,.btn.is-active{transform:translateY(1px)}
.btn:disabled,.btn[aria-disabled="true"]{cursor:not-allowed;opacity:.55;transform:none;box-shadow:none}
.cta-row{display:flex;flex-wrap:wrap;justify-content:center;gap:14px;margin-top:22px}
.text-link{display:inline-flex;align-items:center;gap:8px;min-height:32px;font-weight:var(--weight-semibold)}
.badge{display:inline-flex;align-items:center;gap:10px;min-height:26px;padding:2px 12px 2px 8px;max-width:100%;border-radius:var(--r-pill);background:var(--glass-panel);border:1px solid var(--border);box-shadow:inset 0 1px 0 var(--hi-white-strong);font-size:13px;color:var(--text-muted);overflow-wrap:anywhere}
.badge b{font-weight:var(--weight-semibold);color:var(--text)}
.badge .div{width:1px;height:12px;flex-shrink:0;background:var(--border)}
.announce{position:relative;z-index:5;background:var(--accent);color:var(--text);font-size:var(--text-sm);line-height:20px;padding:8px 20px}
.announce p{margin:0;display:flex;justify-content:center;align-items:center;flex-wrap:wrap;gap:4px 10px;font-weight:var(--weight-medium)}
.announce .sep{opacity:.55}
.announce a{display:inline-flex;align-items:center;gap:6px;margin-left:14px;font-weight:var(--weight-semibold);text-decoration:underline;text-decoration-thickness:1.5px;min-height:24px}
#site-header{position:relative;z-index:60}
.topbar{position:relative;z-index:54;padding-top:10px}
.nav{display:flex;align-items:center;gap:24px;height:52px;padding:0 8px 0 18px;border-radius:var(--r-pill);background:var(--glass-nav);backdrop-filter:blur(14px) saturate(1.2);-webkit-backdrop-filter:blur(14px) saturate(1.2);border:1px solid var(--hi-white);box-shadow:var(--shadow-neutral)}
.topbar>.wrap{width:calc(100% - 48px);max-width:1200px}
.brand{display:inline-flex;align-items:center;gap:10px;text-decoration:none;flex-shrink:0;min-height:32px}
.brand img{width:28px;height:28px;flex-shrink:0}
.brand-en{font-family:var(--font-display);font-weight:var(--weight-bold);font-size:18px;letter-spacing:-.02em;color:var(--text)}
.brand-zh{font-size:var(--text-sm);font-weight:var(--weight-medium);color:var(--text-muted)}
.nav-links{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:28px;flex:1;min-width:0;justify-content:center}
.nav-links li{margin:0;flex-shrink:0}
.nav-links a{display:block;padding:6px 0;text-decoration:none;white-space:nowrap;font-size:14.5px;font-weight:var(--weight-regular);color:var(--text-muted);transition:color .2s}
.nav-links a:hover,.nav-links a[aria-current="page"]{color:var(--text)}
.nav-links a[aria-current="page"]{font-weight:var(--weight-semibold)}
.nav-end{display:flex;align-items:center;gap:6px;flex-shrink:0;margin-left:auto}
.language{position:relative;flex-shrink:0}
.lang{display:inline-flex;align-items:center;justify-content:center;appearance:none;border:0;background:var(--clear);font:inherit;font-size:var(--text-sm);color:var(--text-muted);padding:8px 12px;border-radius:var(--r-pill);min-height:36px;min-width:44px;width:auto;white-space:nowrap;cursor:pointer}
.lang:hover{color:var(--text)}
.lang-panel{position:absolute;right:0;top:calc(100% + 10px);z-index:80;min-width:168px;padding:8px;border:1px solid var(--border);border-radius:var(--r-md);background:var(--panel);box-shadow:var(--shadow-neutral)}
.lang-panel a{display:flex;align-items:center;min-height:40px;padding:8px 12px;text-decoration:none;border-radius:var(--r-sm);white-space:nowrap}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--panel-2);font-weight:var(--weight-semibold)}
.login{display:inline-flex;align-items:center;justify-content:center;height:36px;padding:0 20px;border-radius:var(--r-pill);background:var(--text);color:var(--panel);font-size:var(--text-sm);font-weight:var(--weight-semibold);text-decoration:none;white-space:nowrap;box-shadow:inset 0 1px 0 var(--hi-white-faint),0 6px 16px var(--cool-10)}
.menu-toggle{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;padding:10px;border:0;border-radius:var(--r-pill);background:var(--clear);color:var(--text)}
.menu-line{display:block;width:20px;height:2px;background:currentColor;border-radius:var(--r-pill)}
.nav-drawer{position:fixed;z-index:52;top:var(--header-bottom);right:0;left:0;height:calc(100dvh - var(--header-bottom));max-height:calc(100dvh - var(--header-bottom));padding:16px var(--gutter) 40px;background:var(--panel);overflow-y:auto;overscroll-behavior:contain;border-top:1px solid var(--border)}
.nav-drawer a{display:flex;align-items:center;width:100%;min-height:46px;padding:10px 16px;text-decoration:none;border-radius:var(--r-sm)}
.nav-drawer a:hover,.nav-drawer a[aria-current="page"]{background:var(--panel-2);font-weight:var(--weight-semibold)}
.drawer-languages{border-top:1px solid var(--border);margin-top:16px;padding-top:16px}
.nav-veil{position:fixed;z-index:51;inset:var(--header-bottom) 0 0;background:var(--veil);border:0;width:100%}
html.nav-open{overflow:hidden}
.site-footer{padding-top:64px;padding-bottom:32px;border-top:1px solid var(--border);background:var(--bg-bottom)}
.footer-grid{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:48px}
.footer-grid>*{min-width:0}
.footer-brand p{color:var(--text-muted);font-size:var(--text-sm);max-width:330px;margin-top:18px}
.footer-heading{font-size:var(--text-sm);font-weight:var(--weight-semibold);margin:0 0 16px}
.footer-links{list-style:none;margin:0;padding:0;display:grid;gap:6px}
.footer-links li{margin:0}
.footer-links a{display:inline-flex;align-items:center;min-height:28px;font-size:var(--text-sm);color:var(--text-muted);text-decoration:none}
.footer-links a:hover{text-decoration:underline;color:var(--text)}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 20px;margin-top:40px}
.footer-languages a{display:inline-flex;align-items:center;min-height:30px;font-size:var(--text-sm)}
.footer-bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:16px;margin-top:24px;padding-top:24px;border-top:1px solid var(--border);font-size:var(--text-sm);color:var(--text-muted)}
.footer-bottom p{margin:0}
.footer-legal{display:flex;flex-wrap:wrap;gap:20px}
.footer-legal a{min-height:28px;display:inline-flex;align-items:center}
.reveal{transition:opacity .35s ease,transform .35s ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:static;display:block;min-height:72px;max-width:100%;overflow:hidden;margin-top:24px;margin-bottom:24px}
#server-status+*{margin-top:24px}
.decoration-host,.stripe-halo-host{position:relative;overflow-x:clip;max-width:100%}
.tilt{transform:rotate(.45deg)}
@media(max-width:1250px){
  .nav{gap:16px}
  .nav-links{gap:18px}
  .nav-links a{font-size:13px}
  .lang{padding-inline:8px}
}
@media(max-width:1080px){
  .nav-links{display:none}
  .menu-toggle{display:inline-flex}
  .nav{height:60px;gap:12px;flex-wrap:nowrap}
  .nav-end{margin-left:auto}
}
@media(min-width:1081px){
  .nav-drawer,.nav-veil{display:none!important}
}
@media(max-width:768px){
  h1{font-size:36px;line-height:1.12}
  h2{font-size:28px}
  h3{font-size:21px}
  .sec{padding-top:56px;padding-bottom:56px}
  .grid{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr 1fr;gap:32px}
  .footer-brand{grid-column:1/-1}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .topbar>.wrap{width:calc(100% - 32px)}
  .nav{padding-left:10px;padding-right:4px;gap:6px}
  .announce{font-size:12.5px;padding:7px 16px}
  .announce a{margin-left:6px}
  .brand{gap:6px}
  .brand-en{font-size:16px}
  .brand-zh{font-size:12px}
  .brand img{width:24px;height:24px}
  .lang{font-size:12px;padding-inline:5px}
  .login{padding-inline:13px;font-size:13px}
  .nav-end{gap:2px;margin-left:auto}
  .panel,.card{padding:24px}
  .btn{min-height:44px;font-size:15px;padding:10px 20px}
  .btn-primary{padding:6px 6px 6px 20px}
  .cta-row{gap:10px;margin-top:18px}
  .tilt,[data-tilt]{transform:none}
  .decoration-host,.stripe-halo-host{max-width:100%;overflow-x:clip}
}
@media(max-width:359px){
  .brand-en{font-size:14px}
  .brand img{width:22px;height:22px}
  .lang{font-size:11px;padding-inline:3px}
  .login{padding-inline:10px}
  .nav{gap:3px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending,.reveal.shown{opacity:1;transform:none;transition:none}
  .btn{transition:none}
}