:root {
  color-scheme: light dark;
  --background: #f7f7f9;
  --surface: rgba(255, 255, 255, 0.9);
  --text: #151419;
  --muted: #706e78;
  --border: rgba(21, 20, 25, 0.1);
  --accent: #8b5cf6;
  --accent-dark: #6636cc;
  --accent-soft: #eee8ff;
  --shadow: 0 24px 70px rgba(34, 25, 55, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at 50% -10%, rgba(139, 92, 246, 0.13), transparent 30rem),
    var(--background);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC",
    "PingFang TC", "Noto Sans CJK SC", "Microsoft YaHei", sans-serif;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent-dark);
  text-underline-offset: 0.2em;
}

.site-header {
  position: sticky;
  z-index: 10;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  padding: 12px max(24px, calc((100vw - 980px) / 2));
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--background) 82%, transparent);
  backdrop-filter: blur(18px) saturate(160%);
  -webkit-backdrop-filter: blur(18px) saturate(160%);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-size: 19px;
  font-weight: 750;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 36px;
  height: 36px;
  place-items: center;
  border-radius: 11px;
  color: white;
  background: linear-gradient(145deg, #a77af8, #7044d6);
  box-shadow: 0 8px 20px rgba(112, 68, 214, 0.26);
  font-size: 10px;
  font-weight: 800;
}

.language-switcher {
  display: flex;
  gap: 4px;
  padding: 4px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
}

.language-switcher button {
  min-height: 34px;
  padding: 6px 13px;
  border: 0;
  border-radius: 8px;
  color: var(--muted);
  background: transparent;
  font: inherit;
  font-size: 13px;
  font-weight: 650;
  cursor: pointer;
}

.language-switcher button:hover {
  color: var(--text);
}

.language-switcher button[aria-pressed="true"] {
  color: white;
  background: var(--accent-dark);
  box-shadow: 0 4px 12px rgba(102, 54, 204, 0.24);
}

main {
  width: min(100% - 32px, 900px);
  margin: 56px auto;
}

.policy {
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 28px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.policy[hidden] {
  display: none;
}

.hero {
  padding: 64px 72px 52px;
  border-bottom: 1px solid var(--border);
  background:
    linear-gradient(135deg, rgba(139, 92, 246, 0.11), transparent 65%),
    var(--surface);
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--accent-dark);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.16em;
}

h1 {
  margin: 0;
  font-size: clamp(34px, 6vw, 54px);
  line-height: 1.18;
  letter-spacing: -0.045em;
}

.updated {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.summary {
  max-width: 680px;
  margin: 28px 0 0;
  color: color-mix(in srgb, var(--text) 82%, var(--muted));
  font-size: 18px;
  line-height: 1.75;
}

.principles {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 28px;
}

.principles span {
  padding: 7px 12px;
  border: 1px solid rgba(102, 54, 204, 0.14);
  border-radius: 999px;
  color: var(--accent-dark);
  background: var(--accent-soft);
  font-size: 13px;
  font-weight: 650;
}

section {
  padding: 42px 72px;
  border-bottom: 1px solid var(--border);
}

section:last-child {
  border-bottom: 0;
}

h2 {
  display: flex;
  align-items: baseline;
  gap: 13px;
  margin: 0 0 20px;
  font-size: 23px;
  line-height: 1.35;
  letter-spacing: -0.025em;
}

h2 span {
  color: var(--accent);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.08em;
}

h3 {
  margin: 28px 0 6px;
  font-size: 16px;
}

p,
li {
  color: color-mix(in srgb, var(--text) 78%, var(--muted));
}

section p {
  margin: 0 0 15px;
}

section p:last-child {
  margin-bottom: 0;
}

ul {
  margin: 0;
  padding-left: 1.35em;
}

li + li {
  margin-top: 10px;
}

footer {
  display: flex;
  justify-content: space-between;
  width: min(100% - 48px, 900px);
  margin: -20px auto 48px;
  color: var(--muted);
  font-size: 13px;
}

@media (max-width: 640px) {
  .site-header {
    min-height: 60px;
    padding: 9px 16px;
  }

  .brand-mark {
    width: 32px;
    height: 32px;
  }

  .language-switcher button {
    padding-inline: 10px;
    font-size: 12px;
  }

  main {
    width: min(100% - 20px, 900px);
    margin: 22px auto 46px;
  }

  .policy {
    border-radius: 20px;
  }

  .hero,
  section {
    padding: 34px 24px;
  }

  .summary {
    font-size: 16px;
  }

  footer {
    width: calc(100% - 40px);
    margin-top: -24px;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #111014;
    --surface: rgba(28, 27, 32, 0.92);
    --text: #f5f2fa;
    --muted: #aaa5b3;
    --border: rgba(255, 255, 255, 0.09);
    --accent: #b99af8;
    --accent-dark: #c7adff;
    --accent-soft: rgba(139, 92, 246, 0.14);
    --shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
  }

  .language-switcher button[aria-pressed="true"] {
    color: #17121f;
    background: #c7adff;
  }
}

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