:root {
  --bg: #F9F9F9;
  --panel: #FFFFFF;
  --panel-2: #F1F1F1;
  --border: #E5E5E5;
  --border-strong: #D4D4D4;
  --line-orbit: #DADADA;
  --dot: #D9D9D9;
  --accent: #0A0A0A;
  --accent-dark: #000000;
  --on-accent: #FFFFFF;
  --text: #0A0A0A;
  --muted: #6B6B6B;
  --faint: #9B9B9B;
  --core-hi: #1A1A1A;
  --core-lo: #000000;
  --success: #1F7A4D;
  --warn: #946500;
  --error: #B8322A;
  --veil: rgba(0, 0, 0, 0.18);
  --shade-floor: rgba(0, 0, 0, 0.18);
  --shade-floor-wide: rgba(0, 0, 0, 0.06);
  --shade-core-near: rgba(0, 0, 0, 0.16);
  --shade-core-far: rgba(0, 0, 0, 0.08);
  --shadow-chip: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.04), 0 10px 24px -10px rgba(0, 0, 0, 0.08), 0 44px 80px -28px rgba(0, 0, 0, 0.14);
  --shadow-btn: 0 1px 1px rgba(0, 0, 0, 0.2), 0 10px 22px -10px rgba(0, 0, 0, 0.45);
  --shadow-btn-ghost: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-fab: 0 2px 4px rgba(0, 0, 0, 0.12), 0 18px 36px -12px rgba(0, 0, 0, 0.4);
  --r-card: 20px;
  --r-panel: 28px;
  --r-pill: 999px;
  --r-small: 8px;
  --r-round: 50%;
  --font-display: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-body: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-strong: 600;
  --size-body: 16px;
  --size-small: 14px;
  --size-micro: 12px;
  --size-h1: clamp(34px, 3.35vw, 48px);
  --size-h2: clamp(26px, 2.5vw, 36px);
  --size-h3: 22px;
  --leading-body: 1.6;
  --leading-heading: 1.15;
  --tracking-heading: -0.02em;
  --gutter: 40px;
  --head-h: 72px;
  --width-shell: 1440px;
  --width-body: 1200px;
  --width-reading: 800px;
  --width-header: 1280px;
  --section-space: 120px;
  --orbit-r: 236px;
  --core-size: 300px;
  --duration-fast: 0.2s;
  --duration-reveal: 0.6s;
  --ease: ease;
  --z-header: 100;
  --z-fab: 50;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--head-h) + 24px); }
html, body { margin: 0; padding: 0; }
html.nav-open { overflow: hidden; }
body {
  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;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }
a, button, summary { -webkit-tap-highlight-color: var(--veil); }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
button, input, select, textarea { color: var(--text); }
img, svg, video { max-width: 100%; }
img { display: block; height: auto; }
button svg, a svg, .chrome-dot, .brand-mark { flex-shrink: 0; }
[hidden] { display: none !important; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
::selection { background: var(--accent); color: var(--on-accent); }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: var(--weight-normal);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: var(--size-h1); }
h2 { font-size: var(--size-h2); }
h3 { font-size: var(--size-h3); }
h4 { font-size: var(--size-body); }
p, ul, ol, dl, blockquote, figure { margin-top: 0; }
strong, b { font-weight: var(--weight-strong); }
code, pre, kbd, samp { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; font-size: 0.9em; }
pre {
  min-width: 0;
  max-width: 100%;
  overflow-x: auto;
  padding: 24px;
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  font-size: var(--size-small);
  line-height: 1.8;
  tab-size: 2;
}
pre code { white-space: pre; overflow-wrap: normal; word-break: normal; font-size: inherit; }
hr { border: 0; border-top: 1px solid var(--border); margin-block: 32px; }
.shell, .wrap, .reading {
  width: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.shell { max-width: var(--width-shell); }
.wrap { max-width: calc(var(--width-body) + var(--gutter) * 2); }
.reading { max-width: calc(var(--width-reading) + var(--gutter) * 2); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-head { max-width: 660px; margin-bottom: 48px; }
.section-head h2 { margin: 0; }
.section-head p { margin: 16px 0 0; color: var(--muted); }
.page-intro { padding-top: 80px; padding-bottom: 64px; }
.page-intro h1 { margin: 0 0 24px; }
.page-intro p { max-width: 680px; color: var(--muted); }
.grid { display: grid; gap: 20px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid > *, .hero > *, .footer-grid > *, .feature-tabs > *, .doc-layout > * { min-width: 0; }
.stack > * + * { margin-top: 24px; }
.nowrap { white-space: nowrap; }
.muted { color: var(--muted); }
.mono { font-family: var(--font-mono); }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}
.prose, .article-body { min-width: 0; line-height: 1.9; overflow-wrap: break-word; }
.prose h2, .article-body h2 { margin-top: 64px; margin-bottom: 24px; }
.prose h3, .article-body h3 { margin-top: 36px; margin-bottom: 16px; }
.prose p, .article-body p { margin-bottom: 24px; }
.prose a:not(.btn), .article-body a:not(.btn) { text-decoration: underline; text-underline-offset: 4px; }
.prose li, .article-body li { margin-block: 8px; }
.prose :not(pre) > code, .article-body :not(pre) > code {
  background: var(--panel-2);
  color: var(--text);
  padding: 2px 5px;
  border-radius: var(--r-small);
}
.decorated-section, .hero { overflow-x: clip; position: relative; }

.cta-row, .button-row { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.cta-row { margin-top: 32px; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 48px;
  padding: 10px 24px;
  border: 1px solid var(--border);
  border-radius: var(--r-pill);
  background: var(--panel);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: var(--weight-medium);
  letter-spacing: -0.005em;
  line-height: 1.4;
  text-align: center;
  transition: transform var(--duration-fast) var(--ease), background var(--duration-fast) var(--ease);
}
.btn:hover, .btn.is-hover { transform: translateY(-1px); border-color: var(--border-strong); }
.btn:active, .btn.is-active { transform: translateY(0); background: var(--panel-2); color: var(--text); }
.btn-solid { background: var(--accent); color: var(--on-accent); border-color: var(--accent); box-shadow: var(--shadow-btn); }
.btn-solid:hover, .btn-solid.is-hover, .btn-solid:active, .btn-solid.is-active {
  background: var(--accent-dark);
  color: var(--on-accent);
  border-color: var(--accent-dark);
}
.btn-ghost { background: var(--panel); color: var(--text); box-shadow: var(--shadow-btn-ghost); }
.btn:disabled, .btn[aria-disabled="true"] {
  background: var(--panel-2);
  color: var(--muted);
  border-color: var(--border);
  box-shadow: none;
  transform: none;
  cursor: not-allowed;
}
.btn.is-focus { outline: 2px solid var(--accent); outline-offset: 4px; }
.btn svg { width: 16px; height: 16px; }
.card, .panel {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--border);
}
.card { border-radius: var(--r-card); padding: 28px; box-shadow: var(--shadow-chip); }
.panel { border-radius: var(--r-panel); box-shadow: var(--shadow-card); }
.panel-body { padding: 32px; min-width: 0; }
.card h3 { margin-top: 0; }
.reveal { opacity: 1; transform: none; }
.reveal.is-waiting {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity var(--duration-reveal) var(--ease), transform var(--duration-reveal) var(--ease);
}
.reveal.shown { opacity: 1; transform: none; }

#site-header { position: relative; z-index: var(--z-header); }
.topbar {
  width: 100%;
  max-width: min(100%, calc(var(--width-header) + var(--gutter) * 2));
  margin-inline: auto;
  padding-inline: var(--gutter);
  height: var(--head-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  position: relative;
}
.brand { display: inline-flex; align-items: center; gap: 10px; font-size: 15px; font-weight: var(--weight-medium); letter-spacing: -0.01em; flex-shrink: 0; }
.brand-mark { width: 26px; height: 26px; }
.desktop-nav { min-width: 0; margin-left: auto; }
.topnav-list {
  display: flex;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 32px;
}
.topnav-list a { display: block; padding-block: 12px; font-size: var(--size-small); color: var(--muted); white-space: nowrap; }
.topnav-list a:hover, .topnav-list a[aria-current="page"] { color: var(--text); }
.topnav-list a[aria-current="page"] { font-weight: var(--weight-medium); }
.header-tools { display: flex; align-items: center; gap: 12px; flex-shrink: 0; }
.language-picker { position: relative; }
.lang-switch {
  appearance: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 13px;
  line-height: 1;
  padding: 9px 14px;
  border-radius: var(--r-pill);
  box-shadow: var(--shadow-btn-ghost);
  white-space: nowrap;
}
.lang-switch:hover { border-color: var(--border-strong); }
.lang-short { display: none; }
.language-menu {
  position: absolute;
  top: calc(100% + 12px);
  right: 0;
  width: 180px;
  list-style: none;
  margin: 0;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  background: var(--panel);
  color: var(--text);
  box-shadow: var(--shadow-card);
  z-index: 3;
}
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 10px 14px; border-radius: var(--r-small); font-size: var(--size-small); }
.language-menu a:hover, .language-menu a[aria-current="true"] { background: var(--panel-2); color: var(--text); }
.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-pill);
  background: var(--panel);
  color: var(--text);
}
.menu-toggle svg { width: 20px; height: 20px; }
.mobile-drawer {
  position: absolute;
  top: var(--head-h);
  inset-inline: 0;
  padding: 20px var(--gutter) 28px;
  background: var(--panel);
  color: var(--text);
  border-bottom: 1px solid var(--border);
  max-height: calc(100dvh - var(--head-h));
  overflow-y: auto;
  overscroll-behavior: contain;
  z-index: 2;
}
.mobile-drawer ul { list-style: none; margin: 0; padding: 0; }
.mobile-drawer a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 12px 16px; border-radius: var(--r-small); }
.mobile-drawer a:hover, .mobile-drawer a[aria-current] { background: var(--panel-2); color: var(--text); }
.mobile-languages { margin-top: 20px; padding-top: 20px; border-top: 1px solid var(--border); }
.nav-veil { position: fixed; inset: var(--head-h) 0 0; border: 0; background: var(--veil); color: var(--text); z-index: 1; }
.site-footer { border-top: 1px solid var(--border); padding-top: 64px; padding-bottom: 96px; }
.footer-grid { display: grid; grid-template-columns: 1.2fr 0.7fr 1.3fr 0.7fr; gap: 48px; }
.footer-brand p { color: var(--muted); max-width: 28em; margin: 20px 0 0; font-size: var(--size-small); }
.footer-heading { margin: 0 0 20px; font-size: var(--size-small); font-weight: var(--weight-medium); }
.footer-list { list-style: none; margin: 0; padding: 0; }
.footer-list a { display: inline-block; padding-block: 6px; color: var(--muted); font-size: var(--size-small); }
.footer-list a:hover { color: var(--text); text-decoration: underline; text-underline-offset: 4px; }
.footer-bottom { margin-top: 56px; padding-top: 24px; border-top: 1px solid var(--border); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 16px; color: var(--muted); font-size: 13px; }
.footer-bottom p { margin: 0; }
.preview-menu { display: none; }
.preview-menu summary { list-style: none; }

@media (max-width: 1280px) {
  .topbar { gap: 20px; }
  .topnav-list { gap: 24px; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .desktop-nav { display: none; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .menu-toggle { display: inline-flex; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .header-tools { margin-left: auto; }
}
@media (max-width: 1000px) {
  .desktop-nav { display: none; }
  .menu-toggle { display: inline-flex; }
  .header-tools { margin-left: auto; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .preview-menu { display: block; }
  .preview-menu nav {
    position: absolute;
    top: var(--head-h);
    inset-inline: 0;
    padding: 20px var(--gutter);
    background: var(--panel);
    color: var(--text);
    border-bottom: 1px solid var(--border);
    max-height: calc(100dvh - var(--head-h));
    overflow: auto;
    z-index: 5;
  }
  .preview-menu nav a { display: block; padding: 12px 16px; min-height: 44px; }
}
@media (max-width: 768px) {
  :root { --gutter: 20px; --section-space: 72px; --size-h1: clamp(24px, 5vw, 30px); --size-h2: 26px; }
  .grid-3 { grid-template-columns: 1fr; }
  .page-intro { padding-top: 48px; padding-bottom: 40px; }
}
@media (max-width: 640px) {
  .grid-2, .footer-grid { grid-template-columns: 1fr; }
  .footer-grid { gap: 32px; }
  .topbar { gap: 8px; }
  .header-tools { gap: 8px; margin-left: auto; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .brand { font-size: 13px; gap: 8px; }
  .brand-mark { width: 24px; height: 24px; }
  .card { padding: 24px; }
  .panel-body { padding: 24px; }
  pre { padding: 18px; font-size: 12px; }
  .tilt, [data-tilt] { transform: none !important; }
  .section-head { margin-bottom: 32px; }
}
@media (max-width: 360px) {
  :root { --gutter: 16px; }
  .brand { font-size: 12px; }
  .lang-switch { padding-inline: 10px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal.is-waiting { opacity: 1; transform: none; }
}