:root {
  color-scheme: light;
  font-family: var(--ds-font-sans, -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif);
}

html[data-theme='dark'] {
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--ds-bg-canvas, Canvas);
  color: var(--ds-text-primary, CanvasText);
  font-size: var(--ds-font-size-base, 16px);
  line-height: 1.72;
}

a {
  color: var(--ds-brand, LinkText);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  text-decoration: underline;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--ds-focus-ring, Highlight);
  outline-offset: 2px;
}

body > nav,
body > footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--ds-space-4, 16px);
  padding: var(--ds-space-4, 16px) max(var(--ds-page-gutter, 24px), calc((100vw - var(--ds-layout-content, 1180px)) / 2));
  border-color: var(--ds-border-default, GrayText);
  border-style: solid;
}

body > nav {
  position: sticky;
  z-index: 10;
  top: 0;
  border-width: 0 0 1px;
  background: var(--ds-bg-canvas, Canvas);
}

body > nav > div,
body > footer > div {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--ds-space-2, 8px);
}

body > footer {
  border-width: 1px 0 0;
  color: var(--ds-text-muted, GrayText);
}

.brand {
  color: var(--ds-text-primary, CanvasText);
  font-weight: 700;
  text-decoration: none;
}

.theme-toggle {
  min-height: 36px;
  padding: 0 var(--ds-space-3, 12px);
  border: 1px solid var(--ds-border-default, GrayText);
  border-radius: var(--ds-radius-pill, 999px);
  background: var(--ds-bg-surface, Field);
  color: var(--ds-text-primary, CanvasText);
  font: inherit;
  font-size: var(--ds-font-size-sm, 14px);
  cursor: pointer;
}

main {
  width: min(840px, calc(100% - (2 * var(--ds-page-gutter, 24px))));
  margin: 0 auto;
  padding: var(--ds-space-16, 64px) 0 var(--ds-space-20, 80px);
}

h1,
h2 {
  color: var(--ds-text-primary, CanvasText);
  text-wrap: balance;
}

h1 {
  margin: 0;
  font-size: clamp(var(--ds-font-size-3xl, 32px), 5vw, var(--ds-font-size-5xl, 48px));
  line-height: 1.1;
}

h2 {
  margin: 0 0 var(--ds-space-4, 16px);
  font-size: var(--ds-font-size-xl, 20px);
  line-height: 1.5;
}

p,
li {
  color: var(--ds-text-secondary, GrayText);
}

p {
  margin: var(--ds-space-3, 12px) 0 0;
}

strong,
code {
  color: var(--ds-text-primary, CanvasText);
}

ul,
ol {
  margin: var(--ds-space-3, 12px) 0 0;
  padding-left: var(--ds-space-6, 24px);
}

li + li {
  margin-top: var(--ds-space-2, 8px);
}

.document-header {
  padding-bottom: var(--ds-space-8, 32px);
  border-bottom: 1px solid var(--ds-border-strong, GrayText);
}

.document-meta {
  margin-top: var(--ds-space-4, 16px);
  color: var(--ds-text-muted, GrayText);
  font-size: var(--ds-font-size-sm, 14px);
}

.document-lead {
  margin-top: var(--ds-space-6, 24px);
  color: var(--ds-text-secondary, GrayText);
  font-size: var(--ds-font-size-lg, 18px);
  line-height: 1.75;
}

.document-notice {
  margin-top: var(--ds-space-5, 20px);
  padding-left: var(--ds-space-4, 16px);
  border-left: 3px solid var(--ds-brand, Highlight);
}

.document-toc {
  position: static;
  display: block;
  margin-top: var(--ds-space-10, 40px);
  padding: var(--ds-space-6, 24px) 0;
  border-top: 1px solid var(--ds-border-default, GrayText);
  border-bottom: 1px solid var(--ds-border-default, GrayText);
}

.document-toc h2 {
  font-size: var(--ds-font-size-base, 16px);
}

.document-toc ol {
  columns: 2;
  column-gap: var(--ds-space-8, 32px);
  margin-top: var(--ds-space-4, 16px);
}

.document-toc li {
  break-inside: avoid;
  margin: 0 0 var(--ds-space-2, 8px);
  font-size: var(--ds-font-size-sm, 14px);
}

.legal-section {
  scroll-margin-top: 88px;
  margin-top: var(--ds-space-12, 48px);
  padding-top: var(--ds-space-8, 32px);
  border-top: 1px solid var(--ds-border-default, GrayText);
}

.document-toc + .legal-section {
  border-top: 0;
}

.legal-section > :first-child {
  margin-top: 0;
}

@media (max-width: 640px) {
  body > nav,
  body > footer {
    align-items: flex-start;
    padding-inline: var(--ds-page-gutter-mobile, 16px);
  }

  body > nav {
    position: static;
  }

  body > nav > div {
    justify-content: flex-end;
  }

  main {
    width: calc(100% - (2 * var(--ds-page-gutter-mobile, 16px)));
    padding-block: var(--ds-space-10, 40px) var(--ds-space-16, 64px);
  }

  .document-toc ol {
    columns: 1;
  }
}

@media print {
  body > nav,
  body > footer,
  .theme-toggle {
    display: none;
  }

  body {
    background: Canvas;
    color: CanvasText;
    box-shadow: none;
  }

  main {
    width: 100%;
    padding: 0;
  }

  .legal-section {
    break-inside: avoid-page;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}