:root {
  --bg:#E6EDF8;
  --bg-top:#F3F7FD;
  --panel:#F7FAFE;
  --panel-2:#D9E3F2;
  --border:#C9D5E8;
  --accent:#1C3BEB;
  --accent-dark:#1027B4;
  --accent-soft:#6FB4F7;
  --text:#101828;
  --muted:#55627A;
  --success:#12936B;
  --warn:#C9821A;
  --error:#D23B3B;
  --white:#FFFFFF;
  --clear:transparent;
  --accent-04:rgba(28,59,235,.04);
  --accent-08:rgba(28,59,235,.08);
  --accent-10:rgba(28,59,235,.10);
  --accent-12:rgba(28,59,235,.12);
  --accent-14:rgba(28,59,235,.14);
  --accent-22:rgba(28,59,235,.22);
  --accent-35:rgba(28,59,235,.35);
  --soft-18:rgba(111,180,247,.18);
  --soft-30:rgba(111,180,247,.30);
  --success-12:rgba(18,147,107,.12);
  --warn-12:rgba(201,130,26,.12);
  --error-12:rgba(210,59,59,.12);
  --white-90:rgba(255,255,255,.90);
  --white-22:rgba(255,255,255,.22);
  --white-14:rgba(255,255,255,.14);
  --white-06:rgba(255,255,255,.06);
  --panel-glass:rgba(247,250,254,.88);
  --panel-dim:rgba(247,250,254,.55);
  --panel-legend:rgba(247,250,254,.86);
  --veil:rgba(16,24,40,.30);
  --flag-red:var(--error);
  --flag-blue:var(--accent-dark);
  --radius:6px;
  --radius-sm:3px;
  --radius-control:4px;
  --radius-pill:999px;
  --radius-circle:50%;
  --shadow-card:0 18px 40px -18px var(--accent-22),0 2px 6px var(--accent-08);
  --shadow-cta:0 12px 24px -10px var(--accent-35),inset 0 1px 0 var(--white-22);
  --hl-inset:inset 0 1px 0 var(--white-90);
  --font-display:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Apple SD Gothic Neo","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --fs-xs:11px;
  --fs-label:12px;
  --fs-kicker:13px;
  --fs-small:14px;
  --fs-body:16px;
  --fs-medium:17px;
  --fs-lead:18px;
  --fs-brand:19px;
  --fs-h3:24px;
  --fs-h2:36px;
  --fs-h1:64px;
  --fs-h1-mid:56px;
  --fs-h1-mobile:40px;
  --fs-h2-mobile:28px;
  --weight-normal:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --weight-heavy:800;
  --leading-body:1.6;
  --leading-heading:1.2;
  --tracking-display:-.03em;
  --tracking-cjk:-.02em;
  --gutter:56px;
  --content-width:1240px;
  --header-edge:104px;
  --toc-offset:80px;
  --section-space:72px;
  --motion-fast:.2s;
  --motion-reveal:.35s;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:calc(var(--header-edge) + 16px);scroll-behavior:smooth}
html.nav-open{overflow:hidden}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--fs-body);line-height:var(--leading-body);-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
a,button,summary,select{-webkit-tap-highlight-color:var(--accent-12)}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button,a,summary,select{touch-action:manipulation}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
[hidden]{display:none!important}
img{max-width:100%;height:auto}
svg{vertical-align:middle;flex-shrink:0}
h1,h2,h3,h4,p,figure,blockquote{margin:0}
h1,h2,h3,h4{font-family:var(--font-display);font-weight:var(--weight-heavy);line-height:var(--leading-heading);overflow-wrap:break-word}
h1{font-size:var(--fs-h1);letter-spacing:var(--tracking-display)}
h2{font-size:var(--fs-h2);letter-spacing:var(--tracking-cjk)}
h3{font-size:var(--fs-h3)}
:lang(zh-CN) h1,:lang(zh-TW) h1,:lang(ja) h1,:lang(ko) h1{letter-spacing:var(--tracking-cjk)}
ul,ol{padding-left:1.4em}
code,kbd,pre{font-family:var(--font-mono)}
code{overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:24px;background:var(--text);color:var(--panel);border-radius:var(--radius)}
pre code{overflow-wrap:normal;white-space:pre}
table{border-collapse:collapse}
button:disabled,.btn[aria-disabled="true"]{opacity:.5;cursor:not-allowed}
.wrap{width:100%;max-width:var(--content-width);margin-inline:auto;padding-inline:var(--gutter)}
.section{padding-top:var(--section-space);padding-bottom:var(--section-space)}
.grid{display:grid;gap:24px}
.grid--three{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--five{grid-template-columns:repeat(5,minmax(0,1fr))}
.grid>*{min-width:0}
.no-break{white-space:nowrap}
.muted{color:var(--muted)}
.kw{color:var(--accent)}
.mono{font-family:var(--font-mono)}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
.site{position:relative}
.site::before,.site::after{content:"";position:absolute;top:0;bottom:0;width:1px;background:var(--border);z-index:6;pointer-events:none;left:calc(50% - 620px)}
.site::after{left:calc(50% + 619px)}
.panel,.card{background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--hl-inset),var(--shadow-card);min-width:0}
.card{padding:28px}
.panel--inset{background:var(--panel-2);box-shadow:var(--hl-inset)}
.section-head{margin-bottom:32px;max-width:760px}
.section-head p{margin-top:16px;color:var(--muted);font-size:var(--fs-lead)}
.prose{max-width:800px;min-width:0;overflow-wrap:break-word}
.prose p,.prose ul,.prose ol,.prose pre,.prose table,.prose blockquote{margin-top:20px;margin-bottom:24px}
.prose h2{margin-top:48px;margin-bottom:24px}
.prose h3{margin-top:32px;margin-bottom:16px}
.prose a{text-decoration:underline;text-underline-offset:3px}
.prose li+li{margin-top:8px}
.prose img{display:block}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:48px;padding:12px 26px;border-radius:var(--radius-sm);font-size:var(--fs-body);font-weight:var(--weight-semibold);line-height:1;cursor:pointer;transition:transform var(--motion-fast) ease,background var(--motion-fast) ease,box-shadow var(--motion-fast) ease;border:1px solid var(--clear);flex-shrink:0;white-space:nowrap;text-align:center}
.btn svg{width:16px;height:16px;transition:transform var(--motion-fast) ease}
.btn--primary,.btn-primary{background:linear-gradient(180deg,var(--accent) 0%,var(--accent) 55%,var(--accent-dark) 140%);color:var(--white);box-shadow:var(--shadow-cta)}
.btn--primary:hover,.btn-primary:hover{background:var(--accent-dark);transform:translateY(-1px)}
.btn--primary:hover svg{transform:translateX(3px)}
.btn--ghost{background:var(--panel);color:var(--text);border-color:var(--border);box-shadow:var(--hl-inset),0 6px 16px -10px var(--accent-22)}
.btn--ghost:hover{border-color:var(--muted);transform:translateY(-1px)}
.btn--small{min-height:40px;padding:10px 16px;font-size:var(--fs-small)}
.bracket{--bc:var(--accent);display:inline-flex;padding:6px;background:linear-gradient(var(--bc),var(--bc)) 0 0/10px 2px no-repeat,linear-gradient(var(--bc),var(--bc)) 0 0/2px 10px no-repeat,linear-gradient(var(--bc),var(--bc)) 100% 0/10px 2px no-repeat,linear-gradient(var(--bc),var(--bc)) 100% 0/2px 10px no-repeat,linear-gradient(var(--bc),var(--bc)) 0 100%/10px 2px no-repeat,linear-gradient(var(--bc),var(--bc)) 0 100%/2px 10px no-repeat,linear-gradient(var(--bc),var(--bc)) 100% 100%/10px 2px no-repeat,linear-gradient(var(--bc),var(--bc)) 100% 100%/2px 10px no-repeat}
.bracket--muted{--bc:var(--muted)}
.cta-row{display:flex;flex-wrap:wrap;align-items:center;gap:16px;margin-bottom:32px}
.kicker{display:inline-flex;align-items:center;gap:10px;margin-bottom:24px;font-family:var(--font-mono);font-size:var(--fs-kicker);font-weight:var(--weight-medium);letter-spacing:.16em;color:var(--accent);line-height:1}
.kicker__dot{width:8px;height:8px;flex-shrink:0;border-radius:var(--radius-circle);background:var(--accent);box-shadow:0 0 0 4px var(--accent-12)}
.announce-toggle{position:absolute;width:1px;height:1px;margin:0;opacity:0;pointer-events:none}
.announce{background:var(--accent);color:var(--white);font-size:var(--fs-small);line-height:1.4}
.announce-toggle:checked+.announce{display:none}
.announce__inner{display:flex;align-items:center;justify-content:space-between;gap:24px;min-height:40px}
.announce__text{display:flex;flex-wrap:wrap;align-items:center;gap:4px 10px}
.announce__sep{opacity:.6}
.announce__text a{margin-left:6px;font-weight:var(--weight-semibold);text-decoration:underline;text-underline-offset:3px}
.announce__close{display:inline-flex;align-items:center;justify-content:center;gap:6px;flex:none;min-height:24px;padding:0;border:0;background:var(--clear);color:inherit;font-family:var(--font-mono);font-size:var(--fs-label);letter-spacing:.04em;cursor:pointer;opacity:.88}
.announce__close:hover{opacity:1}
.announce__close svg{width:12px;height:12px}
.announce__close:focus-visible{outline-color:var(--white)}
.announce-toggle:focus-visible+.announce .announce__close{outline:2px solid var(--white);outline-offset:3px}
#site-header{position:relative;z-index:50}
.topbar{position:relative;z-index:53;background:var(--panel-glass);backdrop-filter:blur(10px);border-bottom:1px solid var(--border)}
.topbar__inner{display:flex;align-items:center;gap:24px;height:64px;flex-wrap:nowrap}
.brand{display:inline-flex;align-items:center;gap:10px;flex:none;min-height:44px}
.brand__mark{width:30px;height:30px;flex:none}
.brand__en{font-family:var(--font-display);font-weight:var(--weight-heavy);font-size:var(--fs-brand);letter-spacing:var(--tracking-cjk);line-height:1}
.brand__zh{padding-left:10px;border-left:1px solid var(--border);font-size:var(--fs-small);font-weight:var(--weight-medium);color:var(--muted);line-height:1}
.desktop-nav{position:relative;display:flex;align-items:center;flex:1;min-width:0;gap:2px}
.nav-more{position:relative;flex:none;margin-left:auto}
.nav-more__button{display:flex;align-items:center;min-height:44px;padding:0 8px;border:0;background:var(--clear);font:inherit;font-size:var(--fs-small);color:var(--muted);cursor:pointer;white-space:nowrap}
.nav-more__panel{position:absolute;right:0;top:100%;z-index:60;min-width:220px;padding:8px;list-style:none;margin:0;background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-card)}
.nav-more__panel .tabs__item{height:auto;min-height:44px;white-space:normal;padding:10px 12px}
.tabs{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:2px;min-width:max-content;height:64px}
.tabs li{flex-shrink:0}
.tabs__item{position:relative;display:flex;align-items:center;min-height:44px;height:64px;padding:0 10px;font-size:var(--fs-small);font-weight:var(--weight-medium);color:var(--muted);white-space:nowrap;transition:color var(--motion-fast)}
.tabs__item::after{content:"";position:absolute;left:10px;right:10px;bottom:-1px;height:2px;background:var(--accent);transform:scaleX(0);transform-origin:left center;transition:transform .25s ease,opacity .25s ease;opacity:.35}
.tabs__item:hover{color:var(--text)}
.tabs__item:hover::after{transform:scaleX(1)}
.tabs__item[aria-current="page"]{color:var(--text);font-weight:var(--weight-semibold)}
.tabs__item[aria-current="page"]::after{transform:scaleX(1);opacity:1}
.topbar__tools{display:flex;align-items:center;gap:10px;flex-shrink:0;margin-left:auto}
.language{position:relative;flex:none}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:36px;min-width:44px;width:auto;padding:0 10px;background:var(--clear);border:1px solid var(--clear);border-radius:var(--radius-sm);font-size:var(--fs-small);color:var(--muted);cursor:pointer;white-space:nowrap}
.lang span{white-space:nowrap}
.lang svg{width:16px;height:16px}
.lang:hover{border-color:var(--border);color:var(--text)}
.language__panel{position:absolute;right:0;top:calc(100% + 12px);z-index:60;min-width:180px;padding:8px;background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-card)}
.language__panel a{display:flex;align-items:center;min-height:44px;padding:8px 12px;border-radius:var(--radius-sm)}
.language__panel a:hover,.language__panel a[aria-current="true"]{background:var(--accent-08);color:var(--accent)}
.login{display:inline-flex;align-items:center;justify-content:center;min-height:36px;padding:8px 20px;background:var(--panel);border:1px solid var(--text);border-radius:var(--radius-sm);font-size:var(--fs-small);font-weight:var(--weight-semibold);line-height:1;white-space:nowrap;box-shadow:var(--hl-inset);transition:background var(--motion-fast),color var(--motion-fast)}
.login:hover{background:var(--text);color:var(--white)}
.menu-button{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;padding:10px;background:var(--panel);border:1px solid var(--border);border-radius:var(--radius-sm)}
.menu-button__line{display:block;width:20px;height:2px;background:currentColor}
.drawer{position:fixed;z-index:52;left:0;right:0;top:var(--header-edge);height:calc(100dvh - var(--header-edge));max-height:calc(100dvh - var(--header-edge));overflow-y:auto;overscroll-behavior:contain;background:var(--panel);padding:16px var(--gutter) 32px;border-top:1px solid var(--border)}
.drawer a{display:flex;align-items:center;width:100%;min-height:48px;padding:12px 16px;border-bottom:1px solid var(--border);font-size:var(--fs-body)}
.drawer a[aria-current]{color:var(--accent);background:var(--accent-08)}
.drawer__languages{margin-top:24px;border-top:1px solid var(--border)}
.drawer__label{display:block;padding:12px 16px;color:var(--muted);font-family:var(--font-mono);font-size:var(--fs-label)}
.veil{position:fixed;z-index:51;inset:var(--header-edge) 0 0;background:var(--veil);border:0;width:100%}
.footer{padding-top:56px;padding-bottom:24px;border-top:1px solid var(--border);background:var(--panel-dim)}
.footer__grid{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:48px}
.footer__grid>*{min-width:0}
.footer__intro{margin-top:20px;max-width:350px;color:var(--muted);font-size:var(--fs-small)}
.footer__title{font-family:var(--font-mono);font-size:var(--fs-label);font-weight:var(--weight-semibold);color:var(--muted);margin-bottom:16px}
.footer__links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 20px;list-style:none;padding:0;margin:0}
.footer__links a,.footer__languages a,.footer__legal a{display:inline-flex;align-items:center;min-height:28px;font-size:var(--fs-small)}
.footer a:hover{text-decoration:underline;text-underline-offset:4px}
.footer__languages{display:flex;flex-wrap:wrap;gap:8px 24px;margin-top:36px;padding-top:24px;border-top:1px solid var(--border)}
.footer__bottom{display:flex;flex-wrap:wrap;justify-content:space-between;gap:16px;margin-top:24px;color:var(--muted);font-size:var(--fs-label)}
.footer__legal{display:flex;flex-wrap:wrap;gap:20px}
.reveal{transition:opacity var(--motion-reveal) ease,transform var(--motion-reveal) 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%;overflow:hidden;margin-top:24px;margin-bottom:32px}
#server-status>*{min-width:0;max-width:100%}
#server-status+*{margin-top:32px}
@media(max-width:1260px){.site::before,.site::after{display:none}}
@media(max-width:1180px){
  :root{--gutter:40px}
  .topbar__inner{gap:16px}
  .brand__zh{display:none}
  .tabs__item{padding-inline:8px}
  .footer__grid{gap:32px}
}
@media(max-width:1024px){
  .desktop-nav{display:none}
  .menu-button{display:inline-flex}
  .topbar__tools{margin-left:auto}
}
@media(min-width:1025px){.drawer,.veil{display:none!important}}
@media(max-width:768px){
  :root{--gutter:20px;--fs-h1:40px;--fs-h2:28px;--section-space:48px}
  .topbar__inner{gap:10px}
  .topbar__tools{gap:6px;margin-left:auto}
  .lang{padding-inline:6px;font-size:var(--fs-label)}
  .login{padding-inline:14px}
  .announce{font-size:var(--fs-kicker)}
  .announce__inner{padding-top:8px;padding-bottom:8px;align-items:flex-start}
  .announce__close{font-size:var(--fs-xs)}
  .grid--three,.grid--five{grid-template-columns:1fr}
  .footer__grid{grid-template-columns:1fr;gap:32px}
  .card{padding:24px}
}
@media(max-width:640px){
  .no-break{white-space:normal}
  .tilt,.decorative-tilt,.term{transform:none}
  [data-hero-visual],.decoration-region{max-width:100%;overflow-x:clip}
}
@media(max-width:360px){
  :root{--gutter:16px}
  .brand{gap:6px}
  .brand__en{font-size:var(--fs-body)}
  .brand__mark{width:26px;height:26px}
  .topbar__tools{gap:3px}
  .login{padding-inline:10px}
  .lang{padding-inline:3px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending,.reveal.shown{opacity:1;transform:none;transition:none}
  .btn,.btn svg,.login,.tabs__item::after{transition:none}
}