flow/overflow/scroll.html

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title>CSS Overflow scroll</title>

  <style>
    body {
      font: 1.2em Helvetica, Arial, sans-serif;
      margin: 20px;
      padding: 0;
    }

    textarea {
      font-family: monospace;
      display: block;
      margin-bottom: 10px;
      background-color: #F4F7F8;
      border: none;
      border-left: 6px solid #558ABB;
      color: #4D4E53;
      width: 90%;
      max-width: 700px;
      padding: 10px 10px 0px;
      font-size: 90%;
    }

    textarea:nth-of-type(1) {
      height: 80px
    }

    textarea:nth-of-type(2) {
      height: 160px
    }

    .playable-buttons {
      text-align: right;
      width: 90%;
      max-width: 700px;
      padding: 5px 10px 5px 26px;
      font-size: 100%;
    }

    section {
      width: 90%;
      max-width: 700px;
      border: 1px solid #4D4E53;
      border-radius: 2px;
      padding: 10px 14px 10px 10px;
      margin-bottom: 10px;
    }

    section input {
      display: block;
      margin: 5px;
    }

  </style>
  <style class="editable">
    .box {
        width: 300px;
        height: 100px;
        border: 5px solid rebeccapurple;
        padding: 10px;
        overflow: scroll;
    }
  </style>
</head>

<body>
  <section>
    <div class="box">
      <p>One November night in the year 1782, so the story runs, two brothers sat over their winter fire in the little French town of Annonay, watching the grey smoke-wreaths from the hearth curl up the wide chimney.</p>
     
    </div>
    <p>Their names were Stephen and Joseph Montgolfier, they were papermakers by trade, and were noted as possessing thoughtful minds and a deep interest in all scientific knowledge and new discovery.</p>
    <p>Before that night—a memorable night, as it was to prove—hundreds of millions of people had watched the rising smoke-wreaths of their fires without drawing any special inspiration from the fact.”</p>

  </section>
  <textarea class="playable-css">
.box {
    width: 300px;
    height: 100px;
    border: 5px solid rebeccapurple;
    padding: 10px;
    overflow: scroll;
}
      </textarea>
  <textarea id="code" class="playable-html">
<div class="box">
    <p>One November night in the year 1782, so the story runs, two brothers sat over their winter fire in the little French town of Annonay, watching the grey smoke-wreaths from the hearth curl up the wide chimney.</p> 

</div>
<p>Their names were Stephen and Joseph Montgolfier, they were papermakers by trade, and were noted as possessing thoughtful minds and a deep interest in all scientific knowledge and new discovery.</p>
<p>Before that night—a memorable night, as it was to prove—hundreds of millions of people had watched the rising smoke-wreaths of their fires without drawing any special inspiration from the fact.”</p>
      </textarea>
  <div class="playable-buttons">
    <input id="reset" type="button" value="Reset">
  </div>
</body>
<script>
  var section = document.querySelector('section');
  var editable = document.querySelector('.editable');
  var textareaHTML = document.querySelector('.playable-html');
  var textareaCSS = document.querySelector('.playable-css');
  var reset = document.getElementById('reset');
  var htmlCode = textareaHTML.value;
  var cssCode = textareaCSS.value;

  function fillCode() {
    editable.innerHTML = textareaCSS.value;
    section.innerHTML = textareaHTML.value;
  }

  reset.addEventListener('click', function () {
    textareaHTML.value = htmlCode;
    textareaCSS.value = cssCode;
    fillCode();
  });

  textareaHTML.addEventListener('input', fillCode);
  textareaCSS.addEventListener('input', fillCode);
  window.addEventListener('load', fillCode);
</script>

</html>