body {
  max-width: 850px;
  margin: 3rem auto;
  padding: 0 1.25rem;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  color: #222;
}

header {
  border-bottom: 1px solid #ddd;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
}

nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

nav a {
  color: #0645ad;
  text-decoration: none;
}

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