Untitled

<!DOCTYPE html>
<html>

<head>
  <link href="default.css" rel="stylesheet">
</head>

<body>
  <h1>Hello Plunker!</h1>

    <input id='switch' type="checkbox">

  <script>
    document.querySelector('#switch').onchange = swap;

    function swap(e) {
      document.querySelector('link').href = this.checked ? 'alt.css' : 'default.css';
    }
  </script>
</body>

</html>

// Code goes here

  h1 {
  font: 900 32px/2 Impact;
  }
  input {
    fisplay: block;
    width: 54px;
    height: 54px;
  }

h1 {
  font: 100 54px/1.2 monospace;
}


  input {
    fisplay: block;
    width: 32px;
    height: 32px;
  }