:root {
  color-scheme: light dark;
  --bg: #f2f2f7;
  --text: #1c1c1e;
  --muted: rgba(60, 60, 67, 0.6);
  --link: #007aff;
  --border: rgba(60, 60, 67, 0.18);
  --border-hover: rgba(0, 122, 255, 0.35);
  --surface-strong: rgba(255, 255, 255, 0.92);
  --surface: rgba(255, 255, 255, 0.84);
  --surface-soft: rgba(255, 255, 255, 0.76);
  --bg-overlay: rgba(0, 0, 0, 0.03);
  --btn-bg: rgba(60, 60, 67, 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --text: #f2f2f7;
    --muted: rgba(235, 235, 245, 0.6);
    --link: #0a84ff;
    --border: rgba(84, 84, 88, 0.65);
    --border-hover: rgba(10, 132, 255, 0.45);
    --surface-strong: rgba(28, 28, 30, 0.92);
    --surface: rgba(28, 28, 30, 0.84);
    --surface-soft: rgba(28, 28, 30, 0.76);
    --bg-overlay: rgba(255, 255, 255, 0.04);
    --btn-bg: rgba(235, 235, 245, 0.08);
  }
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, "PingFang SC",
    "Hiragino Sans GB", "Noto Sans CJK SC", "Microsoft YaHei", sans-serif;
  background: linear-gradient(180deg, var(--bg-overlay), transparent 260px), var(--bg);
  color: var(--text);
  line-height: 1.6;
}

a {
  color: var(--link);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

button.btn {
  color: inherit;
  font: inherit;
  cursor: pointer;
}

.nav-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 9px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--btn-bg);
  color: var(--link);
  font: inherit;
  font-weight: 600;
  line-height: 1.2;
  white-space: nowrap;
  user-select: none;
}

.nav-btn:hover {
  text-decoration: none;
  border-color: var(--border-hover);
}

.nav-btn:focus {
  outline: none;
}

.nav-btn:focus-visible {
  outline: 2px solid var(--border-hover);
  outline-offset: 4px;
}

.container {
  max-width: 920px;
  margin: 0 auto;
  padding: 28px 18px 48px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 18px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface-strong);
  backdrop-filter: blur(10px);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.brand-title {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.2px;
}

.brand-subtitle {
  font-size: 12px;
  color: var(--muted);
}

.nav {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: flex-end;
  font-size: 14px;
}

.hero {
  margin-top: 18px;
  padding: 22px 18px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--surface);
}

.hero h1 {
  margin: 0 0 6px;
  font-size: 28px;
  line-height: 1.25;
}

.hero p {
  margin: 0;
  color: var(--muted);
}

.cards {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 14px;
  margin-top: 14px;
}

.card {
  grid-column: span 12;
  padding: 16px 16px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--surface-soft);
}

.card h2 {
  margin: 0 0 6px;
  font-size: 16px;
}

.card p {
  margin: 0;
  color: var(--muted);
}

.card .actions {
  margin-top: 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--btn-bg);
}

.btn:hover {
  text-decoration: none;
  border-color: var(--border-hover);
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #f2f2f7;
  --text: #1c1c1e;
  --muted: rgba(60, 60, 67, 0.6);
  --link: #007aff;
  --border: rgba(60, 60, 67, 0.18);
  --border-hover: rgba(0, 122, 255, 0.35);
  --surface-strong: rgba(255, 255, 255, 0.92);
  --surface: rgba(255, 255, 255, 0.84);
  --surface-soft: rgba(255, 255, 255, 0.76);
  --bg-overlay: rgba(0, 0, 0, 0.03);
  --btn-bg: rgba(60, 60, 67, 0.08);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #000000;
  --text: #f2f2f7;
  --muted: rgba(235, 235, 245, 0.6);
  --link: #0a84ff;
  --border: rgba(84, 84, 88, 0.65);
  --border-hover: rgba(10, 132, 255, 0.45);
  --surface-strong: rgba(28, 28, 30, 0.92);
  --surface: rgba(28, 28, 30, 0.84);
  --surface-soft: rgba(28, 28, 30, 0.76);
  --bg-overlay: rgba(255, 255, 255, 0.04);
  --btn-bg: rgba(235, 235, 245, 0.08);
}

article.policy {
  margin-top: 18px;
  padding: 22px 18px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--surface);
}

article.policy h1 {
  margin-top: 0;
  font-size: 24px;
}

article.policy h2 {
  margin-top: 18px;
  margin-bottom: 8px;
  font-size: 16px;
}

article.policy p,
article.policy li {
  color: var(--text);
}

article.policy .meta {
  color: var(--muted);
  margin-top: 6px;
  margin-bottom: 18px;
}

footer.site-footer {
  margin-top: 22px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 12px;
}

@media (min-width: 720px) {
  .card {
    grid-column: span 6;
  }
}