:root {
  --max-width: 720px;
  --text: #111;
  --muted: #555;
  --link: #0645ad;
  --rule: #e5e5e5;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  color: var(--text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont,
               "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
  background: #fff;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 18px 40px;
}

h1 {
  margin-top: 0;
}

.subtitle {
  color: var(--muted);
  margin-top: 4px;
}

nav {
  margin: 18px 0 24px;
}

nav a {
  margin-right: 16px;
  text-decoration: none;
  color: var(--link);
}

nav a:hover {
  text-decoration: underline;
}

hr {
  border: none;
  border-top: 1px solid var(--rule);
  margin: 24px 0;
}

footer {
  margin-top: 40px;
  padding-top: 12px;
  border-top: 1px solid var(--rule);
  color: var(--muted);
  font-size: 13px;
}