:root {
  --bg: #fafafa;
  --fg: #0f172a;
  --muted: #475569;
  --accent: #2563eb;
  --border: #e5e7eb;
}
[data-theme="dark"] {
  --bg: #020617;
  --fg: #e5e7eb;
  --muted: #94a3b8;
  --accent: #60a5fa;
  --border: #1e293b;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
}
main {
  max-width: 68ch;
  margin: auto;
  padding: 4rem 1.25rem;
}
header { margin-bottom: 4rem; }
nav {
  display: flex;
  gap: 1.25rem;
  align-items: center;
}
nav a {
  color: var(--muted);
  text-decoration: none;
}
nav a:hover { color: var(--fg); }
button {
  margin-left: auto;
  background: none;
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 0.45rem 0.85rem;
  border-radius: 0.5rem;
  font-size: 0.9rem;
  cursor: pointer;
}
button:hover {
  color: var(--fg);
  border-color: var(--accent);
}
h1 {
  font-size: 2.35rem;
  margin: 1rem 0;
  letter-spacing: -0.02em;
}
h2 {
  font-size: 1.25rem;
  margin-top: 3rem;
}
p { margin: 0.75rem 0; }
ul { padding-left: 1.25rem; }
section {
  padding-top: 3rem;
  border-top: 1px solid var(--border);
}
a {
  color: var(--accent);
  text-decoration: none;
}
a:hover { text-decoration: underline; }
footer {
  margin-top: 5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.875rem;
}