:root{
  color-scheme:light;
  --bg:#FAFAF8;
  --panel:#FFFFFF;
  --panel-2:#F1F1EE;
  --panel-soft:#FCFCFA;
  --border:#E3E3DE;
  --border-strong:#CBCBC4;
  --border-hi:#F2F2EE;
  --accent:#131B2E;
  --accent-dark:#090E1A;
  --space-deep:#0A1022;
  --space-abyss:#05080F;
  --planet:#18223B;
  --text:#16181D;
  --muted:#5E626B;
  --success:#1F8A5B;
  --warn:#B7791F;
  --error:#C2412D;
  --amber:#F2A65A;
  --white:#FFFFFF;
  --transparent:transparent;
  --mask-solid:#000000;
  --ink-a04:rgba(19,27,46,.04);
  --ink-a05:rgba(19,27,46,.05);
  --ink-a06:rgba(19,27,46,.06);
  --ink-a08:rgba(19,27,46,.08);
  --ink-a10:rgba(19,27,46,.10);
  --ink-a14:rgba(19,27,46,.14);
  --ink-a18:rgba(19,27,46,.18);
  --ink-a40:rgba(19,27,46,.40);
  --amber-a08:rgba(242,166,90,.08);
  --amber-a14:rgba(242,166,90,.14);
  --amber-a22:rgba(242,166,90,.22);
  --amber-a32:rgba(242,166,90,.32);
  --amber-a50:rgba(242,166,90,.50);
  --amber-a70:rgba(242,166,90,.70);
  --amber-a90:rgba(242,166,90,.90);
  --white-a10:rgba(255,255,255,.10);
  --white-a35:rgba(255,255,255,.35);
  --white-a55:rgba(255,255,255,.55);
  --white-a72:rgba(255,255,255,.72);
  --white-a90:rgba(255,255,255,.90);
  --flag-red:#D3242F;
  --flag-navy:#23315F;
  --flag-black:#1C1C1C;
  --flag-gold:#F2C230;
  --flag-white:#FFFFFF;
  --r-box:28px;
  --r-card:16px;
  --r-menu:18px;
  --r-small:12px;
  --r-tiny:2px;
  --r-pill:999px;
  --r-circle:50%;
  --sh-box:inset 0 1px 0 var(--white),0 1px 2px var(--ink-a06),0 14px 30px -16px var(--ink-a10),0 44px 96px -32px var(--ink-a14);
  --sh-float:0 12px 26px -12px var(--ink-a14),0 2px 6px var(--ink-a06);
  --sh-chip:0 1px 2px var(--ink-a04);
  --sh-card:0 30px 70px -30px var(--ink-a18);
  --sh-menu:0 24px 60px -20px var(--ink-a18),0 2px 8px var(--ink-a06);
  --sh-hover:inset 0 1px 0 var(--white),0 24px 60px -24px var(--ink-a18);
  --font-display:'Inter','Noto Sans SC','PingFang SC','Hiragino Sans','Microsoft YaHei','Malgun Gothic',system-ui,sans-serif;
  --font-body:'Inter','Noto Sans SC','PingFang SC','Hiragino Sans','Microsoft YaHei','Malgun Gothic',system-ui,-apple-system,'Segoe UI',sans-serif;
  --font-mono:'JetBrains Mono',ui-monospace,'SFMono-Regular',Menlo,Consolas,'Liberation Mono',monospace;
  --fs-body:16px;
  --fs-small:14px;
  --fs-meta:13px;
  --fs-h1:clamp(52px,4.6vw,68px);
  --fs-h2:clamp(28px,3vw,40px);
  --fs-h3:24px;
  --weight-body:400;
  --weight-medium:500;
  --weight-semibold:600;
  --weight-bold:700;
  --weight-display:800;
  --gutter:48px;
  --content-width:1440px;
  --reading-width:820px;
  --header-height:72px;
  --anchor-gap:88px;
  --toc-offset:16px;
  --toc-clearance:96px;
  --section-space:80px;
  --ease:cubic-bezier(.2,.7,.2,1);
  --duration-fast:180ms;
  --duration-reveal:600ms;
}
*,*::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(--font-body);font-size:var(--fs-body);font-weight:var(--weight-body);line-height:1.6;-webkit-font-smoothing:antialiased}
[hidden]{display:none!important}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button,summary,a{-webkit-tap-highlight-color:var(--ink-a08)}
button{border:0}
img{display:block;max-width:100%;height:auto}
svg{flex:none;vertical-align:middle}
ul{margin:0;padding:0;list-style:none}
p{margin:0 0 1em}
h1,h2,h3,h4{font-family:var(--font-display);font-weight:var(--weight-bold);color:var(--text);text-wrap:balance;overflow-wrap:break-word}
h1{font-size:var(--fs-h1);line-height:1.1;letter-spacing:-.02em;margin:0 0 24px}
h2{font-size:var(--fs-h2);line-height:1.2;letter-spacing:-.02em;margin:0 0 24px}
h3{font-size:var(--fs-h3);line-height:1.35;letter-spacing:-.015em;margin:0 0 12px}
h4{margin:0 0 12px}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:var(--r-small)}
::selection{background:var(--accent);color:var(--white)}
.no-break{white-space:nowrap}
.wrap{width:100%;max-width:var(--content-width);margin:0 auto;padding-inline:var(--gutter)}
.reading-wrap{max-width:var(--reading-width);margin-inline:auto}
.section{padding-top:var(--section-space);padding-bottom:var(--section-space)}
.section-heading{max-width:var(--reading-width);margin-bottom:32px}
.section-heading p,.muted{color:var(--muted)}
.stack{display:grid;gap:24px}
.grid-two{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:24px}
.grid-three{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}
.grid-two>*,.grid-three>*,.stack>*,.wrap>*{min-width:0}
.panel,.card{min-width:0;background:var(--panel);border:1px solid var(--border);border-top-color:var(--border-hi);border-radius:var(--r-card);box-shadow:var(--sh-box);padding:28px}
.card p:last-child,.panel p:last-child{margin-bottom:0}
.meta{font-size:var(--fs-meta);color:var(--muted);line-height:1.65}
.mono{font-family:var(--font-mono)}
.actions{display:flex;flex-wrap:wrap;align-items:center;gap:12px}
.btn,.pill{display:inline-flex;align-items:center;justify-content:center;gap:8px;border-radius:var(--r-pill);font-weight:var(--weight-semibold);white-space:nowrap;flex-shrink:0;text-align:center;border:1px solid var(--transparent);text-decoration:none;transition:background var(--duration-fast),border-color var(--duration-fast)}
.btn{min-height:44px;padding:9px 20px;font-size:15px;line-height:24px}
.pill{height:40px;padding:0 18px;font-size:14.5px;letter-spacing:-.005em}
.btn-ink,.btn-primary,.pill-ink{background:var(--accent);color:var(--white)}
.btn-ink,.btn-primary{box-shadow:0 8px 20px -8px var(--ink-a18)}
.btn-ink:hover,.btn-primary:hover,.pill-ink:hover,.btn.is-hover{background:var(--accent-dark)}
.btn-soft,.btn-secondary,.pill-soft{background:var(--panel-2);color:var(--text)}
.btn-soft:hover,.btn-secondary:hover,.pill-soft:hover{background:var(--border)}
.btn-outline{background:var(--panel);border-color:var(--border);color:var(--accent)}
.btn-outline:hover{border-color:var(--accent)}
.btn:disabled,.btn[aria-disabled="true"]{background:var(--panel-2);color:var(--muted);box-shadow:none;cursor:not-allowed}
.btn.is-focus{outline:2px solid var(--accent);outline-offset:3px}
.btn-arrow{font-weight:var(--weight-medium)}
.pill-ico{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round}
.text-link{display:inline-flex;align-items:center;min-height:24px;text-decoration:underline;text-underline-offset:4px}
.skip{position:absolute;left:16px;top:-64px;padding:8px 14px;background:var(--accent);color:var(--white);border-radius:var(--r-pill);font-size:var(--fs-small);z-index:30}
.skip:focus{top:12px}
.topbar{position:relative;z-index:10}
.topbar-row{display:flex;align-items:center;height:var(--header-height);gap:40px}
.brand{display:flex;align-items:center;gap:10px;font-family:var(--font-display);font-weight:var(--weight-bold);font-size:18px;letter-spacing:-.02em;color:var(--text);flex-shrink:0}
.brand-mark{display:block;width:32px;height:32px}
.brand-zh{font-weight:var(--weight-medium);color:var(--muted)}
.nav-links{display:flex;align-items:center;gap:4px}
.nav-links>ul{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;height:36px;padding:0 13px;border-radius:var(--r-pill);font-size:15px;color:var(--text);background:var(--transparent);border:0;font-family:inherit;cursor:pointer}
.nav-link:hover{background:var(--ink-a05)}
.nav-link[aria-current="page"],.nav-link.is-current{font-weight:var(--weight-semibold);background:var(--ink-a05)}
.nav-caret{width:12px;height:12px;fill:none;stroke:currentColor;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.nav-more{position:relative}
.nav-more>summary{list-style:none}
.nav-more>summary::-webkit-details-marker{display:none}
.nav-more-panel{position:absolute;top:100%;left:-20px;padding-top:10px}
.menu-card{display:grid;grid-template-columns:1fr 1fr;gap:8px;width:440px;padding:16px;background:var(--panel);border:1px solid var(--border);border-top-color:var(--border-hi);border-radius:var(--r-menu);box-shadow:var(--sh-menu)}
.menu-card>*{min-width:0}
.menu-group-title{display:block;padding:4px 10px 8px;font-family:var(--font-mono);font-size:11px;letter-spacing:.06em;color:var(--muted)}
.menu-item{display:block;padding:10px;border-radius:var(--r-small)}
.menu-item:hover,.menu-item[aria-current="page"]{background:var(--panel-2)}
.menu-item strong{display:block;font-size:var(--fs-small);font-weight:var(--weight-semibold);color:var(--text);line-height:1.4}
.menu-item span{display:block;font-size:12.5px;color:var(--muted);line-height:1.5;margin-top:2px}
.nav-actions{margin-left:auto;display:flex;align-items:center;gap:10px}
.lang-wrap{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:40px;min-width:44px;width:auto;padding:0 12px;border-radius:var(--r-pill);font-size:var(--fs-small);color:var(--muted);background:var(--transparent);border:0;font-family:inherit;cursor:pointer}
.lang-text{white-space:nowrap}
.lang:hover{color:var(--text);background:var(--ink-a05)}
.lang-globe{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:1.3}
.lang-panel{position:absolute;right:0;top:calc(100% + 8px);width:184px;padding:8px;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-menu);box-shadow:var(--sh-menu)}
.lang-panel a{display:flex;align-items:center;min-height:44px;padding:8px 12px;border-radius:var(--r-small)}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--panel-2)}
.menu-toggle{display:none;align-items:center;justify-content:center;min-width:44px;min-height:44px;background:var(--panel-2);border-radius:var(--r-pill);color:var(--accent)}
.menu-toggle svg{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:1.5;stroke-linecap:round}
.mobile-drawer,.nav-veil{display:none}
.site-footer{border-top:1px solid var(--border);background:var(--panel-soft);padding-top:56px;padding-bottom:28px}
.footer-grid{display:grid;grid-template-columns:1.5fr 1.2fr 1fr 1fr;gap:40px}
.footer-grid>*{min-width:0}
.footer-brand p{margin-top:20px;max-width:30em;color:var(--muted);font-size:var(--fs-small)}
.footer-title{font-size:var(--fs-small);font-weight:var(--weight-semibold);margin:0 0 16px}
.footer-links{display:grid;gap:4px}
.footer-links a{display:flex;align-items:center;min-height:32px;font-size:var(--fs-small);color:var(--muted);overflow-wrap:anywhere}
.footer-links a:hover{color:var(--accent);text-decoration:underline;text-underline-offset:4px}
.footer-navigation{grid-template-columns:repeat(2,minmax(0,1fr));column-gap:16px}
.footer-bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:16px;border-top:1px solid var(--border);margin-top:40px;padding-top:24px;color:var(--muted);font-size:var(--fs-meta)}
.footer-legal{display:flex;flex-wrap:wrap;gap:20px}
.footer-legal a{display:inline-flex;align-items:center;min-height:28px}
.prose{overflow-wrap:break-word}
.prose p,.prose li{line-height:1.9}
.prose h2{margin-top:48px}
.prose h3{margin-top:32px}
.prose ul{list-style:disc;padding-left:24px;margin-bottom:24px}
.prose ol{padding-left:24px}
.prose a:not(.btn){text-decoration:underline;text-underline-offset:4px}
code{font-family:var(--font-mono);font-size:.9em;overflow-wrap:anywhere;background:var(--panel-2);padding:2px 5px;border-radius:var(--r-tiny)}
pre{max-width:100%;overflow-x:auto;padding:24px;background:var(--accent);color:var(--white);border-radius:var(--r-card);-webkit-overflow-scrolling:touch}
pre code{background:var(--transparent);padding:0;color:inherit;white-space:pre;overflow-wrap:normal}
.reveal{transition:opacity var(--duration-reveal) var(--ease),transform var(--duration-reveal) var(--ease)}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{display:block;position:relative;min-width:0;max-width:100%;overflow:hidden;margin-top:24px;margin-bottom:24px}
#server-status>*{min-width:0;max-width:100%}
#server-status+*{margin-top:24px}
[data-counter]{display:inline-block;min-width:3ch;font-variant-numeric:tabular-nums}
.decorative-region{position:relative;overflow-x:clip;max-width:100%}
@media(max-width:1180px){
  .lang-text{display:none}
  .topbar-row{gap:24px}
}
@media(max-width:1000px){
  .nav-links{display:none}
  .nav-actions{margin-left:auto}
  .menu-toggle{display:inline-flex}
  html.nav-open{overflow:hidden}
  .mobile-drawer:not([hidden]){display:block;position:fixed;top:var(--header-height);left:0;right:0;max-height:calc(100dvh - var(--header-height));overflow-y:auto;overscroll-behavior:contain;padding:16px var(--gutter) 28px;background:var(--panel);border-top:1px solid var(--border);box-shadow:var(--sh-menu);z-index:12}
  .mobile-drawer a{display:flex;align-items:center;width:100%;min-height:44px;padding:11px 12px;border-radius:var(--r-small)}
  .mobile-drawer a:hover,.mobile-drawer a[aria-current="page"]{background:var(--panel-2)}
  .drawer-languages{border-top:1px solid var(--border);margin-top:16px;padding-top:16px}
  .nav-veil:not([hidden]){display:block;position:fixed;inset:var(--header-height) 0 0;background:var(--ink-a40);z-index:11}
  .footer-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media(max-width:768px){
  :root{--gutter:20px;--header-height:64px;--section-space:48px;--fs-h1:38px;--fs-h2:30px}
  .topbar-row{gap:16px}
  .pill{height:38px;padding:0 14px}
  .grid-three{grid-template-columns:1fr}
  .grid-two{grid-template-columns:1fr}
  .panel,.card{padding:24px}
  .section-heading{margin-bottom:24px}
  .nav-actions{gap:6px;margin-left:auto}
  .nav-actions .lang{padding-inline:8px}
}
@media(max-width:640px){
  .no-break{white-space:normal}
  .nav-cta{display:none}
  .decorative-tilt,.ftag-signup{transform:none}
  .decorative-region{max-width:100%}
  .footer-grid{gap:32px 24px}
  .footer-brand{grid-column:1/-1}
  .footer-bottom{align-items:flex-start;flex-direction:column}
}
@media(max-width:360px){
  :root{--gutter:16px;--fs-h1:34px}
  .brand{font-size:16px;gap:6px}
  .brand-mark{width:28px;height:28px}
  .nav-actions{gap:4px}
  .nav-actions .pill{padding-inline:10px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending{opacity:1;transform:none;transition:none}
  *,*::before,*::after{animation-duration:0.01ms!important;animation-iteration-count:1!important;transition-duration:0.01ms!important}
}