:root {
  --color-page: #f8fafc;
  --color-surface: #ffffff;
  --color-text: #0f172a;
  --color-secondary: #475569;
  --color-border: #e2e8f0;
  --color-accent: #1d4ed8;
  --radius: 16px;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  background: var(--color-page);
  color: var(--color-text);
  font-family:
    system-ui,
    -apple-system,
    'PingFang TC',
    'Noto Sans TC',
    sans-serif;
  line-height: 1.7;
}
main {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 16px 64px;
}
nav {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 32px;
  font-size: 15px;
}
a {
  color: var(--color-accent);
}
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 32px;
}
h1 {
  font-size: 28px;
  margin: 0 0 8px;
}
h2 {
  font-size: 20px;
  margin: 32px 0 8px;
}
.muted {
  color: var(--color-secondary);
  font-size: 14px;
}
.lang {
  border-top: 1px solid var(--color-border);
  margin-top: 40px;
  padding-top: 24px;
}
@media (max-width: 600px) {
  .card {
    padding: 20px;
  }
}