:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #1d1d1f;
  --muted: #6e6e73;
  --accent: #007aff;
  --border: #e5e5ea;
  --card: #f5f5f7;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --fg: #f5f5f7;
    --muted: #a1a1a6;
    --accent: #0a84ff;
    --border: #2c2c2e;
    --card: #1c1c1e;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  -webkit-text-size-adjust: 100%;
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 48px 24px 96px;
}

header.site {
  border-bottom: 1px solid var(--border);
  padding: 16px 24px;
  background: var(--bg);
  position: sticky;
  top: 0;
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  z-index: 10;
}

header.site .inner {
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

header.site .brand {
  font-weight: 700;
  font-size: 17px;
  letter-spacing: -0.01em;
}

header.site nav {
  display: flex;
  gap: 18px;
  font-size: 15px;
}

header.site nav a {
  color: var(--muted);
  text-decoration: none;
}

header.site nav a:hover,
header.site nav a.active {
  color: var(--fg);
}

h1 {
  font-size: 34px;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 0 8px;
  font-weight: 700;
}

h2 {
  font-size: 22px;
  line-height: 1.25;
  letter-spacing: -0.01em;
  margin: 40px 0 12px;
  font-weight: 600;
}

h3 {
  font-size: 18px;
  margin: 24px 0 8px;
  font-weight: 600;
}

p, ul, ol {
  margin: 0 0 14px;
}

ul, ol { padding-left: 22px; }

li { margin-bottom: 6px; }

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

a:hover { text-decoration: underline; }

.lede {
  color: var(--muted);
  font-size: 17px;
  margin-bottom: 32px;
}

.meta {
  color: var(--muted);
  font-size: 14px;
  margin: 0 0 24px;
}

.card {
  background: var(--card);
  border-radius: 14px;
  padding: 18px 20px;
  margin: 16px 0;
}

footer {
  max-width: 720px;
  margin: 48px auto 24px;
  padding: 24px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 14px;
  text-align: center;
}

footer a { color: var(--muted); }

@media (max-width: 480px) {
  main { padding: 32px 20px 64px; }
  h1 { font-size: 28px; }
  h2 { font-size: 20px; }
}