body {
    max-width: 50em;
    margin: 40px auto;
    padding: 0 10px;
    font: 18px/1.5 sans-serif;
    color: #444;
  }
  
  h1,
  h2,
  h3 {
    line-height: 1.2;
  }
  
  @media (prefers-color-scheme: dark) {
    body {
      color: white;
      background: #444;
    }
  
    a:link {
      color: #5bf;
    }
  
    a:visited {
      color: #ccf;
    }
  }