:root{
  --bg:#FBFBFC;
  --bg-panel:#FFFFFF;
  --bg-panel2:#F3F4F6;
  --border:#E3E5EA;
  --accent:#1765D8;
  --accent-dark:#0E4BA8;
  --text:#15171C;
  --text-muted:#5F6570;
  --success:#1F9D55;
  --warn:#E0892E;
  --error:#D2354A;
  --white:#FFFFFF;
  --clear:transparent;
  --accent-2:color-mix(in srgb,var(--accent) 80%,var(--white));
  --wash:color-mix(in srgb,var(--accent) 5%,var(--bg));
  --tint-03:color-mix(in srgb,var(--accent) 3%,transparent);
  --tint-06:color-mix(in srgb,var(--accent) 6%,transparent);
  --tint-08:color-mix(in srgb,var(--accent) 8%,transparent);
  --tint-10:color-mix(in srgb,var(--accent) 10%,transparent);
  --tint-14:color-mix(in srgb,var(--accent) 14%,transparent);
  --tint-24:color-mix(in srgb,var(--accent) 24%,transparent);
  --tint-40:color-mix(in srgb,var(--accent) 40%,transparent);
  --hl:color-mix(in srgb,var(--white) 88%,transparent);
  --hl-soft:color-mix(in srgb,var(--white) 28%,transparent);
  --hair:color-mix(in srgb,var(--border) 72%,var(--white));
  --text-soft:color-mix(in srgb,var(--text-muted) 72%,var(--bg-panel));
  --ink-07:color-mix(in srgb,var(--text) 7%,transparent);
  --glass-top:color-mix(in srgb,var(--bg-panel2) 90%,transparent);
  --glass-bottom:color-mix(in srgb,var(--bg-panel2) 70%,transparent);
  --veil:color-mix(in srgb,var(--bg-panel) 72%,transparent);
  --tag-blue-bg:color-mix(in srgb,var(--accent) 12%,transparent);
  --tag-amber-bg:color-mix(in srgb,var(--warn) 12%,transparent);
  --tag-green-bg:color-mix(in srgb,var(--success) 12%,transparent);
  --warn-ink:color-mix(in srgb,var(--warn) 78%,var(--text));
  --success-ink:color-mix(in srgb,var(--success) 86%,var(--text));
  --success-ring:color-mix(in srgb,var(--success) 18%,transparent);
  --tl-red:#FF5F57;
  --tl-yellow:#FEBC2E;
  --tl-green:#28C840;
  --tl-edge:color-mix(in srgb,var(--text) 12%,transparent);
  --flag-red:#D9283A;
  --flag-white:#FFFFFF;
  --flag-blue:#2B3A8C;
  --flag-edge:color-mix(in srgb,var(--text) 14%,transparent);
  --feature-blue:#EEF4FD;
  --feature-amber:#FDF4EA;
  --font-display:"Inter","Noto Sans SC",-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Hiragino Sans","Apple SD Gothic Neo",sans-serif;
  --font-body:"Inter","Noto Sans SC",-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Hiragino Sans","Apple SD Gothic Neo",sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --r-btn:12px;
  --r-login:9px;
  --r-card:20px;
  --r-win:14px;
  --r-float:12px;
  --r-tag:6px;
  --r-sm:8px;
  --r-item:7px;
  --r-route:10px;
  --r-pill:999px;
  --r-round:50%;
  --shadow-win:0 24px 48px var(--tint-10),0 2px 8px var(--tint-06);
  --shadow-float:0 18px 48px var(--tint-10),0 1px 3px var(--tint-08);
  --shadow-btn:inset 0 1px 0 var(--hl-soft),0 8px 20px var(--tint-24),0 1px 2px var(--tint-14);
  --gutter:24px;
  --content-width:1248px;
  --head-height:60px;
  --anchor-offset:76px;
  --toc-offset:88px;
  --space-section:80px;
  --size-body:15px;
  --size-h1:64px;
  --size-h2:40px;
  --size-h3:24px;
  --weight-display:800;
  --leading-body:1.6;
  --tracking-display:-0.02em;
  --duration-reveal:0.5s;
}
*,*::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:var(--size-body);line-height:var(--leading-body);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}
a{color:inherit}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button:disabled{cursor:not-allowed}
img{max-width:100%;height:auto}
svg{flex-shrink:0}
[hidden]{display:none!important}
:where(a,button,input,select,textarea,summary,[tabindex]):focus-visible{outline:2px solid var(--accent);outline-offset:2px}
h1,h2,h3{font-family:var(--font-display);text-wrap:balance;overflow-wrap:break-word}
h1{margin:0 0 20px;font-weight:var(--weight-display);font-size:clamp(52px,4.45vw,72px);line-height:1.125;letter-spacing:var(--tracking-display)}
h2{margin:0 0 24px;font-size:var(--size-h2);line-height:1.2;font-weight:var(--weight-display);letter-spacing:var(--tracking-display)}
h3{margin:0 0 16px;font-size:var(--size-h3);line-height:1.35}
p{margin:0 0 20px}
code{font-family:var(--font-mono);overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:24px;border:1px solid var(--border);border-radius:var(--r-sm);background:var(--bg-panel2)}
pre code{overflow-wrap:normal;white-space:pre}
.wrap{width:100%;max-width:var(--content-width);margin-inline:auto;padding-inline:var(--gutter);min-width:0}
.sec{padding-top:var(--space-section);padding-bottom:var(--space-section)}
.reading-wrap{max-width:860px}
.prose{min-width:0;overflow-wrap:break-word}
.prose h2,.prose h3{margin-top:48px}
.prose p,.prose li{line-height:1.85}
.prose a{color:var(--accent);text-underline-offset:3px}
.prose li{margin-bottom:8px}
.grid{display:grid;gap:24px}
.grid>*{min-width:0}
.row{display:flex;align-items:center;flex-wrap:wrap;gap:16px}
.row>*{min-width:0}
.muted{color:var(--text-muted)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.kw{color:var(--accent)}
.no-break{white-space:nowrap}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.skip{position:absolute;left:16px;top:-48px;z-index:20;padding:8px 14px;border-radius:var(--r-sm);background:var(--accent-dark);color:var(--white);font-size:14px;text-decoration:none}
.skip:focus{top:12px}
.sprite{position:absolute;width:0;height:0;overflow:hidden}
.ico{display:block;flex:none}
.ln{fill:none;stroke:currentColor;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round}
.fr{fill:var(--flag-red)}
.fw{fill:var(--flag-white)}
.fb{fill:var(--flag-blue)}
.fe{fill:none;stroke:var(--flag-edge);stroke-width:1}
.decor-section{position:relative;overflow-x:clip}
[data-parallax-decor]{pointer-events:none;max-width:100%}
.stage{position:relative;max-width:100%;overflow:hidden;overflow:clip;overflow-x:clip;background:radial-gradient(120% 72% at 50% -12%,var(--wash) 0%,var(--wash) 30%,var(--clear) 72%),linear-gradient(180deg,var(--bg) 0%,var(--bg) 38%,var(--bg-panel2) 100%)}
.site-head,#site-header{position:relative;z-index:30}
.head-in{max-width:var(--content-width);height:var(--head-height);margin:0 auto;padding:0 var(--gutter);display:flex;align-items:center;gap:24px;position:relative}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--text);flex-shrink:0}
.brand img{width:28px;height:28px;flex:none}
.brand-en{font-family:var(--font-display);font-weight:800;font-size:18px;line-height:24px;letter-spacing:-0.01em}
.brand-zh{font-weight:500;font-size:14px;line-height:24px;color:var(--text-muted)}
.nav{margin-left:auto}
.nav ul{display:flex;align-items:center;list-style:none;margin:0;padding:0}
.nav li{display:flex;align-items:center}
.nav li+li::before{content:"·";margin:0 10px;color:var(--text-soft);font-size:14px}
.nav a{padding:6px 0;font-size:14px;line-height:20px;color:var(--text-muted);text-decoration:none;white-space:nowrap;min-height:24px}
.nav a:hover{color:var(--text)}
.nav a[aria-current="page"]{color:var(--text);font-weight:600}
.head-tools{display:flex;align-items:center;gap:12px;flex-shrink:0}
.language-box{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;height:34px;width:auto;min-width:44px;padding:0 8px;border:0;border-radius:var(--r-sm);background:var(--clear);color:var(--text-muted);font:inherit;font-size:14px;cursor:pointer}
.lang span{white-space:nowrap}
.lang:hover{background:var(--ink-07);color:var(--text)}
.lang-caret{font-size:11px}
.language-menu{position:absolute;right:0;top:calc(100% + 8px);width:176px;padding:8px;border:1px solid var(--border);border-radius:var(--r-float);background:var(--bg-panel);box-shadow:var(--shadow-float)}
.language-menu a{display:flex;align-items:center;min-height:44px;padding:8px 12px;text-decoration:none;border-radius:var(--r-sm)}
.language-menu a:hover,.language-menu a[aria-current]{background:var(--tint-08);color:var(--accent)}
.login{display:inline-flex;align-items:center;justify-content:center;height:34px;padding:0 16px;border-radius:var(--r-login);background:var(--accent-dark);color:var(--white);font-size:14px;font-weight:600;text-decoration:none;box-shadow:inset 0 1px 0 var(--hl-soft),0 4px 12px var(--tint-14);white-space:nowrap}
.login:hover{background:var(--accent)}
.menu-toggle{display:none;align-items:center;justify-content:center;min-width:44px;min-height:44px;padding:8px;border:1px solid var(--border);border-radius:var(--r-sm);background:var(--bg-panel);color:var(--text)}
.mobile-nav{display:none}
html.nav-open{overflow:hidden}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;height:48px;padding:0 24px;border:0;border-radius:var(--r-btn);font-size:16px;font-weight:600;line-height:24px;text-decoration:none;flex-shrink:0;white-space:nowrap;max-width:100%}
.btn-primary{color:var(--white);background:linear-gradient(180deg,var(--accent-2) 0%,var(--accent) 100%);box-shadow:var(--shadow-btn)}
.btn-primary:hover,.btn-primary.is-hover{background:linear-gradient(180deg,var(--accent) 0%,var(--accent-dark) 100%)}
.btn-ghost,.btn-secondary{color:var(--text);background:var(--bg-panel);border:1px solid var(--border);box-shadow:inset 0 1px 0 var(--hl),0 1px 2px var(--tint-08)}
.btn-ghost:hover,.btn-secondary:hover{border-color:var(--tint-40)}
.btn:active,.btn.is-pressed{transform:translateY(1px)}
.btn:disabled,.btn[aria-disabled="true"]{opacity:0.55;box-shadow:none}
.btn.is-focus{outline:2px solid var(--accent);outline-offset:2px}
.panel,.card{min-width:0;border:1px solid var(--border);border-radius:var(--r-card);background:var(--bg-panel);padding:32px;box-shadow:var(--shadow-win),inset 0 0 0 1px var(--hl)}
.panel-muted{background:var(--bg-panel2)}
.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:static;display:block;min-width:0;max-width:100%;min-height:48px;overflow:hidden;margin:24px 0}
#server-status>*{min-width:0;max-width:100%}
#server-status+*{margin-top:24px}
.site-foot{border-top:1px solid var(--border);background:var(--bg-panel2);padding-top:56px;padding-bottom:24px}
.foot-grid{display:grid;grid-template-columns:1.25fr 1fr 1fr;gap:48px}
.foot-grid>*{min-width:0}
.foot-brand p{max-width:340px;color:var(--text-muted);margin-top:16px}
.foot-title{font-size:15px;font-weight:700;margin:0 0 16px}
.foot-links{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:1fr 1fr;gap:8px 16px}
.foot-links a,.foot-langs a,.foot-bottom a{display:inline-flex;align-items:center;min-height:28px;text-decoration:none;color:var(--text-muted)}
.foot-links a:hover,.foot-langs a:hover,.foot-bottom a:hover{color:var(--accent)}
.foot-langs{display:flex;flex-wrap:wrap;gap:8px 24px;padding-top:32px;padding-bottom:24px}
.foot-bottom{border-top:1px solid var(--border);padding-top:20px;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px;font-size:13px;color:var(--text-muted)}
.foot-legal{display:flex;flex-wrap:wrap;gap:24px}
@media(max-width:1100px){.head-in{gap:16px}.nav li+li::before{margin:0 6px}.head-tools{gap:8px}}
@media(max-width:960px){
  .head-tools{margin-left:auto}
  .nav{display:none}
  .menu-toggle{display:inline-flex}
  .mobile-nav{position:absolute;left:var(--gutter);right:var(--gutter);top:var(--head-height);background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-win);box-shadow:var(--shadow-float);padding:12px;max-height:calc(100dvh - var(--head-height) - 16px);overflow-y:auto;overscroll-behavior:contain}
  .mobile-nav:not([hidden]){display:block}
  .mobile-nav ul{list-style:none;margin:0;padding:0}
  .mobile-nav a{display:flex;align-items:center;width:100%;min-height:44px;padding:12px 16px;text-decoration:none;border-radius:var(--r-sm)}
  .mobile-nav a:hover,.mobile-nav a[aria-current]{background:var(--tint-08);color:var(--accent)}
  .mobile-languages{border-top:1px solid var(--border);margin-top:12px;padding-top:12px}
  .foot-grid{grid-template-columns:1fr 1fr}
  .foot-brand{grid-column:1/-1}
}
@media(max-width:768px){
  h1{font-size:36px;line-height:44px}
  h2{font-size:30px}
  :root{--space-section:56px}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .head-in{gap:8px}
  .head-tools{gap:4px;margin-left:auto}
  .brand{gap:6px}
  .brand img{width:24px;height:24px}
  .brand-en{font-size:16px}
  .brand-zh{display:none}
  .login{padding:0 12px}
  .lang{padding:0 6px}
  .tilt,[data-tilt]{transform:none}
  [data-parallax-decor]{max-width:100%;transform:none}
  .panel,.card{padding:24px}
  .foot-grid{grid-template-columns:1fr;gap:32px}
  .foot-brand{grid-column:auto}
  .foot-links{gap:12px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none!important;transition:none!important}
  .reveal,.reveal.pending{opacity:1;transform:none}
}