body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
               Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue",
               sans-serif;
  line-height: 1.6;
  max-width: 800px;
  margin: 40px auto;
  padding: 0 16px;
  color: #222;
  background-color: #fff;
}

nav {
  margin-bottom: 16px;
}

nav a {
  text-decoration: none;
  color: #0066cc;
  margin-right: 8px;
}

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

h1 {
  margin-top: 0;
}

hr {
  margin: 24px 0;
}