:root {
  color-scheme: light dark;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
  --accent: #2463eb;
  --surface: rgba(127, 127, 127, 0.10);
  --border: rgba(127, 127, 127, 0.24);
}

* { box-sizing: border-box; }
body { margin: 0; }
main { width: min(860px, calc(100% - 32px)); margin: 0 auto; padding: 48px 0 72px; }
header { margin-bottom: 32px; }
h1 { font-size: clamp(2rem, 7vw, 3.6rem); line-height: 1.08; margin: 0 0 12px; }
h2 { margin-top: 36px; }
h3 { margin-top: 28px; }
p, li { max-width: 74ch; }
.lede { font-size: 1.18rem; opacity: 0.78; }
.card { border: 1px solid var(--border); background: var(--surface); border-radius: 20px; padding: 22px; margin: 18px 0; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 24px 0; }
.button { display: inline-block; text-decoration: none; color: white; background: var(--accent); border: 1px solid var(--accent); border-radius: 999px; padding: 10px 18px; font-weight: 650; }
.button-secondary { color: var(--accent); background: transparent; }
a { color: var(--accent); }
nav { display: flex; gap: 18px; flex-wrap: wrap; margin-top: 28px; }
.meta { opacity: 0.68; font-size: 0.92rem; }
footer { border-top: 1px solid var(--border); margin-top: 48px; padding-top: 20px; opacity: 0.72; }

.site-toolbar { display: flex; align-items: center; justify-content: space-between; gap: 18px; margin-bottom: 46px; }
.brand { color: inherit; font-weight: 750; text-decoration: none; letter-spacing: -0.01em; }
.language-picker { display: inline-flex; align-items: center; gap: 9px; font-size: 0.9rem; opacity: 0.9; }
.language-picker select { appearance: auto; color: inherit; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; padding: 7px 28px 7px 10px; font: inherit; }

html[data-language="zh"] [data-lang="en"],
html[data-language="en"] [data-lang="zh"] { display: none !important; }

@media (max-width: 520px) {
  main { width: min(100% - 24px, 860px); padding-top: 24px; }
  .site-toolbar { margin-bottom: 34px; }
  .language-picker > span { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0, 0, 0, 0); }
}