body {
  font: 15px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  max-width: 640px;
  margin: 4rem auto;
  padding: 0 1.5rem;
  color: #222;
}
code {
  background: #f2f2f2;
  padding: 0.1rem 0.3rem;
  border-radius: 3px;
}