*, *::before, *::after { box-sizing: border-box; }

body {
  font-family: system-ui, sans-serif;
  max-width: 720px;
  margin: 2rem auto;
  padding: 0 1rem;
  color: #222;
}

nav {
  display: flex;
  gap: 1rem;
  margin-bottom: 2rem;
  border-bottom: 1px solid #ddd;
  padding-bottom: 0.75rem;
}

nav a {
  text-decoration: none;
  color: #0066cc;
}

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

h1 { margin-top: 0; }