body {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      font-family: sans-serif;
      background: #f9f9f9;
      margin: 0;
      padding: 20px;
    }
    #rules {
      max-width: 800px;
      text-align: center;
      margin-top: 20px;
      font-size: 18px;
      line-height: 1.6em;
    }