:root{
  color-scheme:light;
  --bg:#F7F2E8;
  --bg-panel:#FFFCF6;
  --bg-panel-2:#EFE8DA;
  --border:#E2D9C7;
  --border-strong:#D4C9B3;
  --accent:#1D2430;
  --accent-hi:#2E3848;
  --accent-dark:#0D1117;
  --on-accent:#FFFCF6;
  --text:#221D16;
  --text-muted:#6E6556;
  --text-faint:#9A907F;
  --success:#2F7A52;
  --warn:#B7791F;
  --error:#B23A2E;
  --hero-top:#FBF7EF;
  --hero-bottom:#F2EBDD;
  --hl-inner:rgba(255,255,255,.92);
  --hl-white-0:rgba(255,255,255,0);
  --hl-white-10:rgba(255,255,255,.10);
  --hl-white-14:rgba(255,255,255,.14);
  --hl-white-18:rgba(255,255,255,.18);
  --hl-white-26:rgba(255,255,255,.26);
  --ink-04:rgba(29,36,48,.04);
  --ink-06:rgba(29,36,48,.06);
  --ink-10:rgba(29,36,48,.10);
  --ink-12:rgba(29,36,48,.12);
  --ink-18:rgba(29,36,48,.18);
  --ink-30:rgba(29,36,48,.30);
  --ink-38:rgba(29,36,48,.38);
  --veil:rgba(29,36,48,.30);
  --halo-1:rgba(255,252,246,.98);
  --halo-2:rgba(255,252,246,.66);
  --halo-3:rgba(255,252,246,.34);
  --halo-ring:rgba(226,217,199,.55);
  --success-ring:rgba(47,122,82,.16);
  --flag-red:#C23A31;
  --flag-white:#FFFDF8;
  --flag-blue:#2A4B8D;
  --flag-navy:#26325F;
  --clear:transparent;
  --font-display:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Apple SD Gothic Neo","Malgun Gothic","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Apple SD Gothic Neo","Malgun Gothic","Microsoft YaHei",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --weight-body:400;
  --weight-medium:500;
  --weight-strong:600;
  --size-body:16px;
  --size-small:14px;
  --size-h1:clamp(52px,4.6vw,66px);
  --size-h2:clamp(28px,3vw,40px);
  --size-h3:22px;
  --r-card:8px;
  --r-tile:8px;
  --r-menu:6px;
  --r-pill:999px;
  --r-circle:50%;
  --shadow-panel:inset 0 1px 0 var(--hl-inner),0 1px 2px var(--ink-06),0 24px 56px -20px var(--ink-10);
  --shadow-chip:inset 0 1px 0 var(--hl-inner),0 10px 26px -10px var(--ink-12),0 1px 2px var(--ink-06);
  --shadow-btn:inset 0 1px 0 var(--hl-white-14),0 10px 24px -12px var(--ink-38),0 1px 2px var(--ink-12);
  --shadow-float:inset 0 1px 0 var(--hl-white-14),0 16px 34px -12px var(--ink-38),0 2px 6px var(--ink-12);
  --nav-h:68px;
  --toc-h:64px;
  --anchor-offset:148px;
  --lock-y:155px;
  --gutter:clamp(20px,3.4vw,48px);
  --wrap-max:1456px;
  --reading-max:840px;
  --section-space:96px;
  --ease:200ms ease;
  --reveal-time:350ms;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:calc(var(--nav-h) + 16px)}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--size-body);font-weight:var(--weight-body);line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
[hidden]{display:none!important}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button,a,summary{touch-action:manipulation}
button{border:0}
:where(a,button,summary,input,select,textarea,[tabindex]):focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:var(--r-menu)}
img,svg,video{max-width:100%;vertical-align:middle}
img{height:auto}
svg{flex-shrink:0}
h1,h2,h3,h4{font-family:var(--font-display);font-weight:var(--weight-medium);overflow-wrap:break-word;text-wrap:balance}
h1{font-size:var(--size-h1);line-height:1.12;letter-spacing:-.02em}
h2{font-size:var(--size-h2);line-height:1.25;letter-spacing:-.02em}
h3{font-size:var(--size-h3);line-height:1.4;letter-spacing:-.01em}
p,li{overflow-wrap:break-word}
code{font-family:var(--font-mono);overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:24px;background:var(--bg-panel-2);border:1px solid var(--border);border-radius:var(--r-card)}
pre code{white-space:pre;overflow-wrap:normal}
hr{border:0;border-top:1px solid var(--border);margin-block:32px}
.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}
.wrap{width:100%;max-width:var(--wrap-max);margin-inline:auto;padding-inline:var(--gutter)}
.reading-wrap{width:100%;max-width:var(--reading-max);margin-inline:auto;padding-inline:var(--gutter)}
.sec{padding-top:var(--section-space);padding-bottom:var(--section-space)}
.grid{display:grid;gap:24px}
.grid>*,:where(.wrap,.reading-wrap,main,article,section,nav,header,footer)>*{min-width:0}
.grid--three{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--five{grid-template-columns:repeat(5,minmax(0,1fr))}
.stack>*+*{margin-top:24px}
.muted{color:var(--text-muted)}
.mono{font-family:var(--font-mono)}
.kicker{font-family:var(--font-mono);font-size:12px;letter-spacing:.08em;color:var(--text-muted)}
.prose{line-height:1.85}
.prose h2{margin-top:56px}
.prose h3{margin-top:32px}
.prose p{margin-block:20px}
.prose a:not(.btn){text-decoration:underline;text-underline-offset:4px}
.prose ul,.prose ol{padding-left:24px}
.panel,.card{background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-card);box-shadow:var(--shadow-panel)}
.card{padding:24px}
.btn,.btn-login{display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;white-space:nowrap}
.btn{gap:8px;min-height:48px;padding:10px 26px;border:1px solid var(--clear);border-radius:var(--r-pill);font-size:15.5px;font-weight:var(--weight-medium);letter-spacing:-.005em;text-align:center;transition:transform var(--ease),box-shadow var(--ease),border-color var(--ease)}
.btn:hover{transform:translateY(-1px)}
.btn--primary,.btn-primary{background:linear-gradient(180deg,var(--accent-hi),var(--accent) 60%,var(--accent-dark));color:var(--on-accent);box-shadow:var(--shadow-btn)}
.btn--ghost{background:var(--bg-panel);color:var(--text);border-color:var(--border);box-shadow:var(--shadow-chip)}
.btn--ghost:hover{border-color:var(--border-strong)}
.btn:active{transform:translateY(0)}
.btn:disabled,.btn[aria-disabled="true"]{opacity:.5;cursor:not-allowed;transform:none;box-shadow:none}
.cta-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:32px}
#site-header{position:relative;z-index:70;min-height:var(--nav-h)}
.topbar{position:relative;z-index:72;height:var(--nav-h);display:flex;align-items:center;flex-wrap:nowrap;gap:40px;padding:0 var(--gutter)}
.brand{display:inline-flex;align-items:center;gap:10px;flex-shrink:0;font-family:var(--font-display);font-size:17px;font-weight:var(--weight-strong);letter-spacing:-.015em;min-height:36px}
.brand__mark{display:block;width:28px;height:28px;flex:none}
.brand__zh{font-weight:var(--weight-body);color:var(--text-muted)}
.nav{display:flex;align-items:center;flex:1;min-width:0}
.nav ul{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:2px}
.nav__link,.nav-more__btn{display:inline-flex;align-items:center;gap:4px;min-height:40px;padding:8px 12px;border-radius:var(--r-pill);font:inherit;font-size:14.5px;color:var(--text-muted);background:var(--clear);border:0;cursor:pointer;white-space:nowrap;transition:color var(--ease),background-color var(--ease)}
.nav__link:hover,.nav-more__btn:hover{color:var(--text);background:var(--ink-04)}
.nav__link[aria-current="page"],.nav-more__item[aria-current="page"]{color:var(--text);font-weight:var(--weight-strong)}
.nav-more{position:relative}
.nav-more__btn svg{width:10px;height:10px;display:block}
.nav-more__btn{list-style:none}
.nav-more__btn::-webkit-details-marker{display:none}
.nav-more__menu{position:absolute;top:calc(100% + 8px);left:0;z-index:80;min-width:244px;padding:8px;background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-card);box-shadow:var(--shadow-panel)}
.nav-more__group{display:block;padding:4px 10px 6px;font-family:var(--font-mono);font-size:10.5px;letter-spacing:.08em;color:var(--text-muted)}
.nav-more__item{display:block;padding:9px 10px;border-radius:var(--r-menu)}
.nav-more__item:hover{background:var(--bg-panel-2)}
.nav-more__item b{display:block;font-size:14px;font-weight:var(--weight-medium)}
.nav-more__item small{display:block;font-size:12px;color:var(--text-muted)}
.topbar__end{margin-left:auto;display:flex;align-items:center;gap:10px;flex-shrink:0}
.lang-picker{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-width:44px;min-height:40px;width:auto;padding:8px 10px;border:0;background:var(--clear);border-radius:var(--r-pill);font:inherit;font-size:14px;color:var(--text-muted);white-space:nowrap}
.lang:hover{background:var(--ink-04);color:var(--text)}
.lang svg{width:15px;height:15px;display:block}
.lang__text{white-space:nowrap}
.lang-panel{position:absolute;right:0;top:calc(100% + 8px);z-index:85;min-width:180px;padding:8px;background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-card);box-shadow:var(--shadow-panel)}
.lang-panel a{display:flex;align-items:center;width:100%;min-height:44px;padding:8px 12px;border-radius:var(--r-menu)}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--bg-panel-2)}
.btn-login{height:36px;padding:0 18px;border-radius:var(--r-pill);border:1px solid var(--border);background:var(--bg-panel);box-shadow:var(--shadow-chip);font-size:14px;font-weight:var(--weight-medium);transition:border-color var(--ease),transform var(--ease)}
.btn-login:hover{border-color:var(--border-strong);transform:translateY(-1px)}
.menu-toggle{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;border-radius:var(--r-pill);background:var(--clear);color:var(--text)}
.menu-toggle__line{display:block;width:20px;height:2px;background:currentColor}
.mobile-nav{position:fixed;top:var(--nav-h);right:0;left:0;z-index:71;height:calc(100dvh - var(--nav-h));max-height:calc(100dvh - var(--nav-h));overflow-y:auto;overscroll-behavior:contain;padding:20px var(--gutter) 40px;background:var(--bg-panel);border-top:1px solid var(--border)}
.mobile-nav a{display:flex;align-items:center;width:100%;min-height:48px;padding:12px 16px;border-radius:var(--r-menu)}
.mobile-nav a:hover,.mobile-nav a[aria-current="page"]{background:var(--bg-panel-2)}
.mobile-nav__label{display:block;margin:24px 16px 8px;color:var(--text-muted);font-size:12px}
.nav-veil{position:fixed;inset:var(--nav-h) 0 0;z-index:70;background:var(--veil)}
html.nav-open{overflow:hidden}
.nav-drawer{display:none;position:relative}
.nav-drawer summary{list-style:none;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;min-height:44px;min-width:44px;padding:0 10px;border-radius:var(--r-pill);font-size:14px}
.nav-drawer summary::-webkit-details-marker{display:none}
.nav-drawer__panel{position:absolute;right:0;top:calc(100% + 8px);z-index:85;min-width:220px;max-height:calc(100dvh - var(--nav-h) - 16px);overflow-y:auto;padding:8px;background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--r-card);box-shadow:var(--shadow-panel)}
.nav-drawer__panel a{display:flex;align-items:center;width:100%;min-height:44px;padding:10px 12px;border-radius:var(--r-menu)}
.nav-drawer__panel a:hover{background:var(--bg-panel-2)}
.site-footer{border-top:1px solid var(--border);padding-top:64px;padding-bottom:32px;background:var(--bg-panel-2)}
.footer-grid{display:grid;grid-template-columns:minmax(0,1.4fr) repeat(3,minmax(0,1fr));gap:40px}
.footer-brand p{max-width:30em;color:var(--text-muted);font-size:14px}
.footer-heading{margin:0 0 16px;font-size:14px;font-weight:var(--weight-strong)}
.footer-links{list-style:none;margin:0;padding:0;display:grid;gap:6px}
.footer-links a{display:inline-flex;align-items:center;min-height:28px;font-size:14px;color:var(--text-muted)}
.footer-links a:hover{text-decoration:underline;text-underline-offset:4px;color:var(--text)}
.footer-bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:16px;margin-top:48px;padding-top:24px;border-top:1px solid var(--border);font-size:12px;color:var(--text-muted)}
.footer-legal{display:flex;flex-wrap:wrap;gap:16px}
.footer-legal a{display:inline-flex;align-items:center;min-height:28px}
.reveal{transition:opacity var(--reveal-time) ease,transform var(--reveal-time) ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:relative;display:block;min-height:160px;max-width:100%;overflow:hidden;margin-block:32px}
#server-status+*{margin-top:32px}
#server-status>*{min-width:0;max-width:100%}
.decor-region{position:relative;overflow-x:clip;max-width:100%}
.counter{display:inline-block;min-width:3ch;font-family:var(--font-mono);font-variant-numeric:tabular-nums;text-align:right}
@media(max-width:1180px){
  .topbar{gap:24px}
  .nav__link,.nav-more__btn{padding-inline:9px}
}
@media(max-width:1000px){
  .nav{display:none}
  .menu-toggle{display:inline-flex}
  .topbar__end{margin-left:auto}
  .nav-drawer{display:block}
  .footer-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media(min-width:1001px){
  .mobile-nav,.nav-veil{display:none!important}
  html.nav-open{overflow:auto}
}
@media(max-width:768px){
  :root{--size-h1:clamp(28px,8vw,40px);--section-space:64px}
  .grid--three{grid-template-columns:minmax(0,1fr)}
  .grid--five{grid-template-columns:repeat(2,minmax(0,1fr))}
  .lang__text{display:none}
}
@media(max-width:640px){
  .no-break{white-space:normal}
  .topbar{gap:10px}
  .topbar__end{gap:2px;margin-left:auto}
  .brand{font-size:15px;gap:7px}
  .brand__mark{width:25px;height:25px}
  .btn-login{padding-inline:12px;font-size:13px}
  .lang{padding-inline:8px}
  .tilt,[data-tilt]{transform:none}
  .decor-region{max-width:100%}
  .footer-grid{grid-template-columns:minmax(0,1fr);gap:32px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending,.reveal.shown{opacity:1;transform:none;transition:none}
  *,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}
}