:root {
  --bg: #ffffff;
  --fg: #1f2328;
  --muted: #656d76;
  --line: #d8dee4;
  --accent: #0969da;
  --card: #f6f8fa;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --fg: #e6edf3;
    --muted: #8b949e;
    --line: #30363d;
    --accent: #4493f8;
    --card: #161b22;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

.wrap {
  max-width: 940px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  border-bottom: 1px solid var(--line);
  padding: 14px 0;
}

.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.02em;
  color: var(--fg);
  text-decoration: none;
}

.brand span { color: var(--accent); }

nav a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 18px;
  font-size: 14px;
}

nav a:hover { color: var(--accent); }

.hero {
  padding: 56px 0 32px;
  border-bottom: 1px solid var(--line);
}

.hero h1 {
  margin: 0 0 12px;
  font-size: 34px;
  line-height: 1.2;
  letter-spacing: -0.03em;
}

.lead {
  margin: 0;
  color: var(--muted);
  max-width: 60ch;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  padding: 32px 0;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 18px;
}

.card h2 {
  margin: 0 0 8px;
  font-size: 15px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.card p { margin: 0; font-size: 15px; }

.note {
  padding: 8px 0 48px;
}

.note h2 { font-size: 18px; margin: 0 0 8px; }
.note p { margin: 0; color: var(--muted); max-width: 68ch; }

.site-footer {
  border-top: 1px solid var(--line);
  padding: 20px 0;
}

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