index.html

<!DOCTYPE html>
<html>
  <title>react-rebound demo</title>
  <head>
    <style>
      h1, h2, body, button {
        font: 16px/24px -apple-system, BlinkMacSystemFont, sans-serif;
      }
      body {
        max-width: 600px;
        padding: 0 20px;
        margin: 0 auto;
      }
      a {
        color: #6699CC;
        text-decoration: none;
      }
      h1 {
        font-weight: bold;
        font-size: 24px;
      }
      h2 {
        margin: 0;
        padding: 0;
        font-weight: bold;
        margin-bottom: 5px;
      }
      section {
        padding: 20px 0;
        border-bottom: 1px solid #eee;
      }
      button {
        background: teal;
        color: white;
        padding: 10px 20px;
        border: none;
        outline: none;
      }
      .c1 {background: #EC5f67;}
      .c2 {background: #F99157;}
      .c3 {background: #FAC863;}
      .c4 {background: #99C794;}
      .c5 {background: #5FB3B3;}
      .c6 {background: #6699CC;}
      .c7 {background: #C594C5;}
      .loading {
        font-size: 24px;
        line-height: 36px;
        text-align: center;
        position: relative;
        color: #ccc;
        top: 50vh;
        transform: translateY(-50%);
        white-space: pre-wrap;
      }
    </style>
  </head>
  <body>
    <div id="wrapper"></div>
    <script src="./demo.js"></script>
  </body>
</html>