:root {
  color-scheme: light;
  --bg: #F4F4F3;
  --bg-panel: #FFFFFF;
  --bg-panel-2: #EBEBEA;
  --bg-sheet: #FAFAF9;
  --border: #E2E2E0;
  --border-soft: #EDEDEB;
  --guide: #DADAD7;
  --guide-strong: #C4C4C0;
  --dot: #DCDCD9;
  --accent: #292A2E;
  --accent-dark: #16171A;
  --accent-mate: #3A4558;
  --text: #1C1C1F;
  --text-2: #3C3C42;
  --text-muted: #6B6B71;
  --text-faint: #9A9AA0;
  --success: #1E8A55;
  --warn: #B7791F;
  --error: #C8372D;
  --success-rgb: 30 138 85;
  --slate-rgb: 54 65 82;
  --white-rgb: 255 255 255;
  --ink-rgb: 22 23 26;
  --flag-white: #FFFFFF;
  --flag-jp-red: #BC002D;
  --flag-us-red: #B22234;
  --flag-us-blue: #3C3B6E;
  --flag-hk-red: #DE2910;
  --flag-sg-red: #EE2536;
  --flag-de-black: #1A1A1A;
  --flag-de-red: #DD0000;
  --flag-de-gold: #FFCE00;
  --flag-edge: rgb(var(--ink-rgb) / .14);
  --font-display: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans", "Apple SD Gothic Neo", "Microsoft YaHei", system-ui, sans-serif;
  --font-body: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans", "Yu Gothic", "Apple SD Gothic Neo", "Malgun Gothic", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --r-hero: 20px;
  --r-window: 12px;
  --r-card: 12px;
  --r-cell: 7px;
  --r-small: 8px;
  --r-input: 10px;
  --r-mark: 3px;
  --r-circle: 50%;
  --r-pill: 999px;
  --gutter: 24px;
  --page-width: 1376px;
  --reading-width: 800px;
  --header-height: 72px;
  --toc-offset: 16px;
  --anchor-offset: 96px;
  --hover: rgb(var(--slate-rgb) / .06);
  --veil: rgb(var(--ink-rgb) / .22);
  --gradient-primary: linear-gradient(100deg, var(--accent), var(--accent-mate));
  --gradient-cell: linear-gradient(160deg, var(--accent), var(--accent-mate));
  --gradient-sheet: linear-gradient(180deg, var(--bg-sheet), var(--bg-panel));
  --gradient-control: linear-gradient(180deg, var(--bg-panel), var(--bg-panel-2));
  --shadow-hero: inset 0 1px 0 rgb(var(--white-rgb) / 1), 0 48px 96px -40px rgb(var(--slate-rgb) / .10), 0 16px 40px -18px rgb(var(--slate-rgb) / .10), 0 1px 2px rgb(var(--slate-rgb) / .05);
  --shadow-window: inset 0 1px 0 rgb(var(--white-rgb) / 1), 0 28px 56px -28px rgb(var(--slate-rgb) / .16), 0 6px 16px -6px rgb(var(--slate-rgb) / .07);
  --shadow-sheet: 0 -8px 22px -14px rgb(var(--slate-rgb) / .20);
  --shadow-chip: inset 0 1px 0 rgb(var(--white-rgb) / 1), 0 14px 28px -12px rgb(var(--slate-rgb) / .26), 0 2px 4px rgb(var(--slate-rgb) / .08);
  --shadow-cta: inset 0 1px 0 rgb(var(--white-rgb) / .16), 0 16px 30px -16px rgb(var(--slate-rgb) / .60), 0 2px 4px rgb(var(--slate-rgb) / .14);
  --shadow-soft: 0 1px 2px rgb(var(--slate-rgb) / .06);
  --shadow-icon: inset 0 1px 0 rgb(var(--white-rgb) / 1), 0 6px 12px -8px rgb(var(--slate-rgb) / .30);
  --shadow-inset: inset 0 1px 2px rgb(var(--slate-rgb) / .12);
  --shadow-selected: 0 2px 6px -1px rgb(var(--slate-rgb) / .20), 0 0 0 1px rgb(var(--slate-rgb) / .06);
  --shadow-login: inset 0 1px 0 rgb(var(--white-rgb) / .14), 0 8px 16px -10px rgb(var(--slate-rgb) / .60);
  --shadow-float: inset 0 1px 0 rgb(var(--white-rgb) / .14), 0 18px 32px -14px rgb(var(--slate-rgb) / .55);
  --ease: cubic-bezier(.2, .7, .2, 1);
  --time-fast: .15s;
  --time-reveal: .5s;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: var(--anchor-offset); scroll-behavior: smooth; }
body {
  min-height: 100vh;
  font: 15px/1.6 var(--font-body);
  color: var(--text);
  background-color: var(--bg);
  background-image: linear-gradient(180deg, rgb(var(--slate-rgb) / .03) 0, rgb(var(--slate-rgb) / .07) 860px, rgb(var(--slate-rgb) / .07) 100%);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; cursor: pointer; }
button:disabled { cursor: not-allowed; }
img { display: block; max-width: 100%; height: auto; }
svg { display: block; flex-shrink: 0; }
ul { list-style: none; }
[hidden] { display: none !important; }
:where(a, button, summary, input, select, textarea, [tabindex]):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--r-small);
}
:where(button, summary, select) { min-height: 24px; }
h1, h2, h3, h4 { font-family: var(--font-display); text-wrap: balance; overflow-wrap: break-word; }
h1 { font-size: clamp(52px, 4.72vw, 68px); font-weight: 800; line-height: 1.1; letter-spacing: -.02em; }
h2 { font-size: clamp(28px, 3vw, 40px); font-weight: 750; line-height: 1.22; letter-spacing: -.02em; }
h3 { font-size: 21px; font-weight: 700; line-height: 1.35; letter-spacing: -.015em; }
p { overflow-wrap: break-word; }
code { font-family: var(--font-mono); overflow-wrap: anywhere; }
pre { max-width: 100%; overflow-x: auto; padding: 20px; background: var(--bg-panel-2); border: 1px solid var(--border); border-radius: var(--r-card); }
pre code { white-space: pre; overflow-wrap: normal; }
input, select, textarea { max-width: 100%; padding: 10px 14px; background: var(--bg-panel); border: 1px solid var(--border); border-radius: var(--r-input); }
input:focus, select:focus, textarea:focus { border-color: var(--accent); }
.mono { font-family: var(--font-mono); }
.no-break { white-space: nowrap; }
.muted { color: var(--text-muted); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.wrap { width: 100%; max-width: var(--page-width); padding-inline: var(--gutter); margin-inline: auto; }
.reading-wrap { width: 100%; max-width: var(--reading-width); padding-inline: var(--gutter); margin-inline: auto; }
.section { padding-top: 64px; padding-bottom: 64px; }
.section-head { max-width: 720px; margin: 0 auto 32px; text-align: center; }
.section-head h2 { margin-top: 18px; }
.section-head p { margin-top: 16px; color: var(--text-muted); font-size: 17px; }
.section-head .actions { justify-content: center; margin-top: 24px; }
.actions { display: flex; align-items: center; flex-wrap: wrap; gap: 12px; }
.grid-three { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.grid-five { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 16px; }
.grid-three > *, .grid-five > *, .wrap > *, .reading-wrap > * { min-width: 0; }
.panel, .card { background: var(--bg-panel); border: 1px solid var(--border); border-radius: var(--r-card); box-shadow: var(--shadow-window); padding: 28px; min-width: 0; }
.panel h3 + p, .card h3 + p { margin-top: 12px; color: var(--text-muted); }
.btn, .btn-primary, .btn-ghost, .btn-secondary {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 48px; gap: 8px; padding: 10px 22px;
  font-size: 15px; font-weight: 600; border-radius: var(--r-pill);
  flex-shrink: 0; white-space: nowrap;
  transition: background-color var(--time-fast), border-color var(--time-fast), transform var(--time-fast);
}
.btn-primary { min-height: 52px; background: var(--gradient-primary); color: var(--bg-panel); box-shadow: var(--shadow-cta); font-size: 16px; letter-spacing: .01em; }
.btn-primary:hover { transform: translateY(-1px); }
.btn-ghost, .btn-secondary { background: linear-gradient(180deg, var(--bg-panel), var(--bg)); border: 1px solid var(--border); color: var(--text); box-shadow: var(--shadow-soft); }
.btn-ghost:hover, .btn-secondary:hover { border-color: var(--guide-strong); background: var(--bg-panel-2); }
.btn { background: var(--bg-panel-2); color: var(--text); }
.btn:hover { background: var(--hover); }
:where(.btn, .btn-primary, .btn-ghost, .btn-secondary) svg { width: 18px; height: 18px; }
:where(.btn, .btn-primary, .btn-ghost, .btn-secondary)[aria-disabled="true"],
:where(.btn, .btn-primary, .btn-ghost, .btn-secondary):disabled { background: var(--bg-panel-2); color: var(--text-muted); box-shadow: none; transform: none; cursor: not-allowed; }
.btn.is-demo-hover { background: var(--accent-dark); color: var(--bg-panel); }
.btn.is-demo-focus { outline: 2px solid var(--accent); outline-offset: 3px; }

.frame { position: relative; max-width: var(--page-width); margin: 0 auto; padding: 0 24px 120px; min-height: 100vh; overflow-x: clip; }
.frame::before, .frame::after { content: ""; position: absolute; top: 0; bottom: 0; width: 1px; background: var(--guide); pointer-events: none; }
.frame::before { left: 0; }
.frame::after { right: 0; }
.cross { position: absolute; width: 17px; height: 17px; pointer-events: none; z-index: 2; }
.cross::before, .cross::after { content: ""; position: absolute; background: var(--guide-strong); }
.cross::before { left: 8px; top: 0; width: 1px; height: 17px; }
.cross::after { top: 8px; left: 0; width: 17px; height: 1px; }
.x-tl { top: -8px; left: -8px; }
.x-tr { top: -8px; right: -8px; }
.x-bl { bottom: -8px; left: -8px; }
.x-br { bottom: -8px; right: -8px; }
.section-rule { position: relative; height: 1px; background: var(--guide); margin-block: 32px; }

#site-header { position: relative; z-index: 40; min-height: var(--header-height); }
.topbar {
  position: relative; z-index: 40;
  display: grid; grid-template-columns: auto 1fr auto;
  align-items: center; gap: 32px; height: var(--header-height); padding: 0 48px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; min-height: 44px; flex-shrink: 0; }
.brand img { width: 28px; height: 28px; flex: none; }
.brand-en { font-family: var(--font-display); font-weight: 800; font-size: 19px; letter-spacing: -.02em; color: var(--text); }
.brand-zh { font-size: 13px; font-weight: 500; color: var(--text-muted); padding-left: 10px; border-left: 1px solid var(--border); line-height: 1.2; }
.nav { justify-self: center; }
.nav-list { display: flex; align-items: center; list-style: none; margin: 0; padding: 0; gap: 2px; }
.nav-list > li > a, .nav-more-btn {
  display: inline-flex; align-items: center; gap: 4px; min-height: 36px; padding: 0 14px;
  border-radius: var(--r-pill); font-size: 14.5px; color: var(--text-2); white-space: nowrap;
  transition: background-color var(--time-fast), color var(--time-fast);
}
.nav-list > li > a:hover, .nav-more-btn:hover { background: var(--hover); color: var(--text); }
.nav-list a[aria-current="page"], .nav-more-btn.is-current { color: var(--text); font-weight: 600; }
.nav-more { position: relative; }
.nav-menu {
  position: absolute; top: 100%; left: 50%; min-width: 220px; margin-top: 8px; padding: 8px;
  transform: translateX(-50%); background: var(--bg-panel); border: 1px solid var(--border);
  border-radius: var(--r-card); box-shadow: var(--shadow-window); display: none;
}
.nav-more.is-open .nav-menu, .nav-more:focus-within .nav-menu { display: block; }
.menu-group { padding: 8px 10px 4px; font-size: 11.5px; font-weight: 500; color: var(--text-muted); }
.nav-menu a { display: flex; align-items: center; min-height: 40px; padding: 8px 10px; border-radius: var(--r-small); font-size: 14px; color: var(--text-2); }
.nav-menu a:hover { background: var(--bg); color: var(--text); }
.nav-tools { display: flex; align-items: center; gap: 8px; min-width: 0; }
.lang-control { position: relative; }
.lang { display: inline-flex; align-items: center; justify-content: center; gap: 6px; height: 36px; width: auto; min-width: 44px; padding: 0 12px; border-radius: var(--r-pill); font-size: 14px; color: var(--text-2); white-space: nowrap; }
.lang:hover { background: var(--hover); }
.lang span { white-space: nowrap; }
.lang-menu { position: absolute; top: calc(100% + 8px); right: 0; width: 180px; padding: 8px; background: var(--bg-panel); border: 1px solid var(--border); border-radius: var(--r-card); box-shadow: var(--shadow-window); }
.lang-menu a { display: flex; align-items: center; min-height: 44px; padding: 8px 12px; border-radius: var(--r-small); }
.lang-menu a:hover, .lang-menu a[aria-current="true"] { background: var(--bg-panel-2); }
.login { display: inline-flex; align-items: center; justify-content: center; gap: 6px; height: 38px; padding: 0 14px 0 18px; border-radius: var(--r-pill); background: var(--accent); color: var(--bg-panel); font-size: 14px; font-weight: 600; white-space: nowrap; box-shadow: var(--shadow-login); }
.login:hover { background: var(--accent-dark); }
.login svg { width: 14px; height: 14px; }
.menu-toggle { display: none; min-width: 44px; min-height: 44px; border: 1px solid var(--border); border-radius: var(--r-pill); background: var(--bg-panel); }
.menu-toggle svg { width: 20px; height: 20px; margin: auto; }
.mobile-nav { display: none; }
.nav-veil { display: none; }
html.nav-open { overflow: hidden; }

.site-footer { border-top: 1px solid var(--border); background: var(--bg-sheet); padding-top: 48px; padding-bottom: 24px; }
.footer-grid { display: grid; grid-template-columns: minmax(0, 1.4fr) repeat(3, minmax(0, 1fr)); gap: 32px; }
.footer-grid > * { min-width: 0; }
.footer-intro p { color: var(--text-muted); max-width: 330px; margin-top: 16px; }
.footer-title { font-size: 14px; font-weight: 650; margin-bottom: 12px; }
.footer-links { display: grid; gap: 4px; }
.footer-links a { display: inline-flex; align-items: center; min-height: 32px; padding-block: 3px; font-size: 14px; color: var(--text-2); overflow-wrap: anywhere; }
.footer-links a:hover { text-decoration: underline; text-underline-offset: 4px; }
.footer-bottom { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 16px; margin-top: 36px; padding-top: 20px; border-top: 1px solid var(--border); font-size: 13px; 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; }
.prose { line-height: 1.85; overflow-wrap: break-word; }
.prose h2 { margin-top: 48px; margin-bottom: 20px; font-size: 30px; }
.prose h3 { margin-top: 28px; margin-bottom: 12px; }
.prose p + p { margin-top: 18px; }
.prose ul, .prose ol { padding-left: 24px; margin-block: 20px; }
.prose ul { list-style: disc; }
.prose li + li { margin-top: 8px; }
.prose a { text-decoration: underline; text-underline-offset: 4px; overflow-wrap: anywhere; }
.prose pre { margin-block: 24px; }
.prose code { font-size: .9em; background: var(--bg-panel-2); border-radius: var(--r-mark); }
.prose pre code { background: none; }
.reveal { transition: opacity var(--time-reveal) var(--ease), transform var(--time-reveal) var(--ease); }
.reveal.pending { opacity: 0; transform: translateY(16px); }
.reveal.shown { opacity: 1; transform: none; }
[data-counter] { display: inline-block; min-width: 3ch; font-variant-numeric: tabular-nums; font-family: var(--font-mono); text-align: end; }
.motion-line-mask { display: block; overflow: clip; }
.motion-line { display: block; }
#server-status { display: block; position: static; min-width: 0; max-width: 100%; min-height: 120px; overflow: hidden; margin-block: 24px; }
#server-status + * { margin-top: 24px; }
.decoration-host { position: relative; overflow-x: clip; }
.decoration-host > [aria-hidden="true"] { max-width: 100%; }

@media (hover: hover) {
  .nav-more:hover .nav-menu { display: block; }
}
@media (max-width: 1180px) {
  .topbar { padding-inline: 36px; gap: 20px; }
  .nav-list > li > a, .nav-more-btn { padding-inline: 10px; }
}
@media (max-width: 960px) {
  .topbar { display: flex; justify-content: space-between; padding-inline: 24px; gap: 12px; }
  .nav { display: none; }
  .nav-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; align-items: center; justify-content: center; }
  .mobile-nav:not([hidden]) {
    display: block; position: absolute; top: var(--header-height); left: 0; right: 0;
    z-index: 44; max-height: calc(100dvh - var(--header-height)); overflow-y: auto;
    overscroll-behavior: contain; padding: 16px 24px 24px;
    background: var(--bg-panel); border: 1px solid var(--border); box-shadow: var(--shadow-window);
  }
  .mobile-nav a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 12px 16px; border-radius: var(--r-small); }
  .mobile-nav a:hover, .mobile-nav a[aria-current="page"] { background: var(--bg-panel-2); }
  .mobile-nav .menu-group { padding-inline: 16px; }
  .nav-veil:not([hidden]) { display: block; position: fixed; inset: var(--header-height) 0 0; z-index: 30; background: var(--veil); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid-five { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  h1 { font-size: 38px; }
  h2 { font-size: 30px; }
  .frame { padding: 0 16px 96px; }
  .topbar { padding-inline: 8px; }
  .section { padding-top: 40px; padding-bottom: 40px; }
  .grid-three { grid-template-columns: minmax(0, 1fr); }
  .grid-five { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .panel, .card { padding: 22px; }
  .prose h2 { font-size: 26px; }
}
@media (max-width: 640px) {
  :root { --gutter: 16px; }
  .no-break { white-space: normal; }
  .tilt, [data-tilt] { transform: none; }
  .decoration-host > [aria-hidden="true"] { max-width: 100%; }
  .topbar { gap: 8px; }
  .brand { gap: 6px; }
  .brand-en { font-size: 17px; }
  .nav-tools { gap: 4px; margin-left: auto; }
  .lang { padding-inline: 8px; }
  .lang-label { display: none; }
  .login { min-height: 44px; padding-inline: 14px; }
  .footer-grid { gap: 28px 20px; }
  .footer-intro { grid-column: 1 / -1; }
  .footer-bottom { align-items: flex-start; flex-direction: column; }
  .actions > a { max-width: 100%; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0s !important; animation-duration: 0s !important; }
  .reveal, .reveal.pending { opacity: 1; transform: none; }
  .btn-primary:hover { transform: none; }
}