index.html

<html>

<head>
  <meta charset="UTF-8" />
  <script src="/node_modules/browser-cjs/require.js"></script>

  <link rel="stylesheet" href="/node_modules/codemirror/lib/codemirror.css">
  <link href="notebook.css" rel="stylesheet" />
</head>

<body dir="auto">
  <div class="source-with-result">
    <div class="source">
      <textarea dir="auto" class="source" id="source"> white black
   fade slow
blue
swap

red yellow fade
yellow green fade 
glue
green cyan fade
glue
cyan blue fade
glue
blue purple fade
glue

copy
slow
swap

copy
copy reverse glue
</textarea>
    </div>
    <div class="result" id="result">
      <div class="before-stack"></div>
      <div class="stack"></div>
      <div class="after-stack"></div>
    </div>
  </div>

  <script src="notebook.js"></script>
</body>

</html>