:root{
  --bg:#F5F4F6;
  --bg-deep:#EDEBF0;
  --panel:#FFFFFF;
  --panel-2:#ECEBEF;
  --border:#DEDCE3;
  --accent:#FF4B91;
  --accent-dark:#D42370;
  --apricot:#FF9B52;
  --ink:#17151D;
  --muted:#5E5A68;
  --success:#1E9E6A;
  --warn:#D98A0B;
  --error:#D93A2B;
  --ink-2:#211E29;
  --ink-3:#2C2834;
  --track-off:#3A3642;
  --knob-off:#8C8797;
  --knob-shade:#F3E4EC;
  --on-ink:#F5F4F6;
  --on-ink-muted:#A39EAF;
  --ink-line:rgba(255,255,255,.08);
  --ink-hi:rgba(255,255,255,.10);
  --grid-line:rgba(23,21,29,.04);
  --glow-pink:rgba(255,75,145,.07);
  --glow-apricot:rgba(255,155,82,.06);
  --pink-06:rgba(255,75,145,.06);
  --pink-10:rgba(255,75,145,.10);
  --pink-14:rgba(255,75,145,.14);
  --pink-18:rgba(255,75,145,.18);
  --pink-40:rgba(255,75,145,.40);
  --pink-dark-45:rgba(212,35,112,.45);
  --apricot-12:rgba(255,155,82,.12);
  --apricot-20:rgba(255,155,82,.20);
  --ink-06:rgba(23,21,29,.06);
  --ink-10:rgba(23,21,29,.10);
  --ink-30:rgba(23,21,29,.30);
  --black-35:rgba(0,0,0,.35);
  --white-25:rgba(255,255,255,.25);
  --white-45:rgba(255,255,255,.45);
  --hi:rgba(255,255,255,.95);
  --chip-iepl-bg:rgba(255,75,145,.16);
  --chip-iepl-fg:#FF8FBA;
  --chip-relay-bg:rgba(217,138,11,.18);
  --chip-relay-fg:#F2B650;
  --chip-direct-bg:rgba(30,158,106,.22);
  --chip-direct-fg:#56D39F;
  --flag-red:#D22F3A;
  --flag-blue:#2B3A8C;
  --flag-navy:#1E2A6E;
  --flag-green:#1F8A4C;
  --flag-white:#FFFFFF;
  --mask-solid:#000000;
  --mask-clear:transparent;
  --grad-hot:linear-gradient(100deg,var(--accent) 0%,var(--apricot) 100%);
  --grad-soft:linear-gradient(90deg,var(--pink-10) 0%,var(--apricot-12) 100%);
  --grad-soft-strong:linear-gradient(90deg,var(--pink-18) 0%,var(--apricot-20) 100%);
  --shadow-card:inset 0 1px 0 var(--hi),0 1px 2px var(--ink-06),0 14px 28px -16px var(--pink-10),0 32px 64px -24px var(--pink-10);
  --shadow-deep:inset 0 1px 0 var(--ink-hi),0 40px 80px -32px var(--ink-30),0 28px 64px -24px var(--pink-14);
  --shadow-hot:inset 0 1px 0 var(--white-45),0 8px 20px -8px var(--pink-40);
  --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","Microsoft YaHei","Malgun Gothic",system-ui,sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --r-sm:8px;
  --r-md:10px;
  --r-lg:12px;
  --r-pill:999px;
  --gutter:32px;
  --anchor-offset:96px;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:var(--anchor-offset);-webkit-text-size-adjust:100%}
html.nav-open{overflow:hidden}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font-body);font-size:16px;line-height:1.5;-webkit-font-smoothing:antialiased;overflow-x:clip}
a{color:inherit;text-decoration:none}
button,input{font:inherit}
button{cursor:pointer}
a:focus-visible,button:focus-visible,summary:focus-visible,[role="tab"]:focus-visible,select:focus-visible,input:focus-visible{outline:2px solid var(--accent-dark);outline-offset:3px}
ul{list-style:none;margin:0;padding:0}
p{margin:0}
img,svg{vertical-align:middle}
img{max-width:100%;height:auto}
svg{flex-shrink:0}
h1,h2,h3{font-family:var(--font-display);text-wrap:balance;overflow-wrap:break-word}
h1{font-size:clamp(52px,5vw,72px);line-height:1.1}
h2{font-size:clamp(30px,3.4vw,44px);line-height:1.15}
h3{font-size:clamp(21px,2vw,27px);line-height:1.25}
code{font-family:var(--font-mono);overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:20px;border-radius:var(--r-md);background:var(--ink);color:var(--on-ink)}
pre code{overflow-wrap:normal}
.wrap{width:100%;max-width:1296px;margin-inline:auto;padding-inline:var(--gutter);min-width:0}
.mono{font-family:var(--font-mono)}
.no-break{white-space:nowrap}
.kw{background:var(--grad-hot);-webkit-background-clip:text;background-clip:text;color:var(--mask-clear);-webkit-text-fill-color:var(--mask-clear);padding-bottom:.04em}
.sec{padding-top:72px;padding-bottom:72px}
.sec-head{margin:0 0 24px}
.eyebrow{font-family:var(--font-mono);font-size:12px;font-weight:700;color:var(--accent-dark);letter-spacing:.04em}
.panel,.card{background:var(--panel);border:1px solid var(--border);border-radius:var(--r-lg);box-shadow:var(--shadow-card)}
.panel{padding:24px}
.reveal{transition:opacity .55s ease,transform .55s ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
[data-count]{font-variant-numeric:tabular-nums;display:inline-block;min-width:3ch}

/* Shared header: the brand, navigation, tools and drawer are siblings. */
.topbar{position:relative;z-index:30;background:var(--bg)}
.topbar-in{display:grid;grid-template-columns:auto minmax(0,1fr) auto;align-items:center;gap:24px;min-height:64px}
.brand{display:inline-flex;align-items:center;gap:10px;white-space:nowrap;min-height:44px}
.brand img{width:30px;height:30px;flex-shrink:0}
.brand-en{font-family:var(--font-display);font-weight:900;font-size:19px;letter-spacing:-.03em;color:var(--ink)}
.brand-zh{font-size:14px;font-weight:500;color:var(--muted)}
.navline{justify-self:center;min-width:0}
.navline ul{display:flex;align-items:center;list-style:none;margin:0;padding:5px 8px;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-pill);box-shadow:var(--shadow-card)}
.navline li{display:flex;align-items:center;white-space:nowrap}
.navline li+li::before{content:"·";color:var(--knob-off);font-weight:700;margin:0 2px}
.navline a{display:flex;align-items:center;min-height:34px;padding:6px 11px;font-size:14px;font-weight:500;color:var(--muted);border-radius:var(--r-pill)}
.navline a:hover{color:var(--ink)}
.navline a[aria-current="page"]{color:var(--ink);font-weight:700;background:var(--panel-2)}
.topbar-end{display:flex;align-items:center;justify-content:flex-end;gap:8px;min-width:0}
.lang-box{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-width:44px;min-height:38px;width:auto;padding:0 12px;border:0;background:transparent;font-size:14px;font-weight:600;color:var(--ink);border-radius:var(--r-pill);white-space:nowrap}
.lang:hover{background:var(--panel-2)}
.lang-caret{font-size:11px;color:var(--muted)}
.lang-menu{position:absolute;right:0;top:calc(100% + 8px);min-width:150px;padding:6px;background:var(--panel);border:1px solid var(--border);border-radius:var(--r-md);box-shadow:var(--shadow-card);z-index:35}
.lang-menu[hidden]{display:none}
.lang-menu a{display:flex;align-items:center;min-height:40px;padding:8px 12px;border-radius:var(--r-sm);white-space:nowrap}
.lang-menu a:hover,.lang-menu a[aria-current]{background:var(--panel-2)}
.menu-toggle{display:none;align-items:center;justify-content:center;min-width:44px;min-height:44px;border:1px solid var(--border);border-radius:var(--r-md);background:var(--panel);color:var(--ink)}
.mobile-nav{display:none}
.mobile-nav[hidden]{display:none}
.btn-hot,.btn-line,.btn-secondary{display:inline-flex;align-items:center;justify-content:center;gap:8px;white-space:nowrap;flex-shrink:0;font-weight:800}
.btn-hot{height:44px;padding:0 22px;border:0;border-radius:var(--r-pill);background:var(--grad-hot);color:var(--ink);font-size:16px;box-shadow:var(--shadow-hot)}
.btn-hot:hover{filter:saturate(1.08) brightness(1.03)}
.btn-sm{height:38px;padding:0 16px;font-size:14px}
.btn-arrow{font-family:var(--font-mono);font-weight:700}
.btn-line,.btn-secondary{min-height:56px;padding:0 26px;border-radius:var(--r-pill);border:1px solid var(--ink);color:var(--ink);background:transparent;font-size:16px}
.btn-line:hover,.btn-secondary:hover{background:var(--panel)}
.btn-hot:disabled,.btn-line:disabled,.btn-secondary:disabled{opacity:.48;cursor:not-allowed}
.btn-hot:active,.btn-line:active,.btn-secondary:active{transform:translateY(1px)}

/* Shared footer */
.site-footer{padding-top:56px;background:var(--ink);color:var(--on-ink)}
.footer-grid{display:grid;grid-template-columns:1.5fr 1fr 1.4fr 1fr;gap:32px;padding-bottom:40px}
.footer-brand{display:inline-flex;align-items:center;gap:10px;font-size:20px;font-weight:900}
.footer-brand img{width:32px;height:32px}
.footer-desc{max-width:290px;margin-top:16px;color:var(--on-ink-muted);font-size:14px}
.footer-title{margin:0 0 14px;font-size:13px;font-weight:800}
.footer-links{display:flex;flex-direction:column;gap:4px}
.footer-links a{display:inline-flex;align-items:center;min-height:32px;color:var(--on-ink-muted);font-size:13px}
.footer-links a:hover{color:var(--on-ink)}
.footer-bottom{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;padding-top:20px;padding-bottom:24px;border-top:1px solid var(--ink-line);color:var(--on-ink-muted);font-family:var(--font-mono);font-size:12px}
.footer-legal{display:flex;flex-wrap:wrap;gap:20px}
.footer-legal a:hover{color:var(--on-ink)}

@media(max-width:1100px){
  .navline a{padding:6px 8px;font-size:13px}
  .brand-zh{display:none}
}
@media(max-width:980px){
  .topbar-in{grid-template-columns:auto 1fr;gap:8px;min-height:64px}
  .navline{display:none}
  .topbar-end{margin-left:auto}
  .menu-toggle{display:inline-flex}
  .mobile-nav:not([hidden]){display:block;position:absolute;top:100%;left:0;right:0;max-height:calc(100dvh - 64px);overflow-y:auto;overscroll-behavior:contain;background:var(--panel);border-top:1px solid var(--border);box-shadow:var(--shadow-card);padding:12px var(--gutter) 20px;z-index:31}
  .mobile-nav ul{display:block;list-style:none;margin:0;padding:0}
  .mobile-nav a{display:flex;width:100%;align-items:center;min-height:48px;padding:12px 14px;border-radius:var(--r-sm);font-weight:600}
  .mobile-nav a:hover,.mobile-nav a[aria-current]{background:var(--panel-2)}
  .mobile-nav-label{padding:14px 14px 6px;color:var(--muted);font-size:12px;font-family:var(--font-mono)}
  .mobile-nav-languages{border-top:1px solid var(--border);margin-top:10px}
}
@media(max-width:768px){
  h1{font-size:clamp(28px,8vw,40px);letter-spacing:-.02em}
  .sec{padding-top:56px;padding-bottom:56px}
  .footer-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media(max-width:640px){
  :root{--gutter:18px;--anchor-offset:84px}
  .no-break{white-space:normal}
  .wrap{padding-inline:var(--gutter)}
  .tilt,[class*="tilt-"]{transform:none}
  .footer-grid{gap:28px}
  .topbar-end{gap:4px}
  .topbar-end .lang{padding-inline:6px}
  .topbar-end .btn-sm{padding-inline:12px}
  .mobile-nav:not([hidden]){max-width:100%}
}
@media(max-width:370px){
  :root{--gutter:16px}
  .topbar-end .lang{font-size:12px}
  .brand-en{font-size:17px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending{transition:none;opacity:1;transform:none}
}