title: css how to make max-width fixed when adding padding
body: <p>I just wondering is there any way that could make max-width become fixed when padding left and right is being added?</p>
  <p>Here my css:</p>
  <pre class="lang-css prettyprint-override"><code>#editorBody {
    overflow: auto;
    margin: auto;
    padding: 15px 40px 10px 40px;
    max-width: 816px; 
  }
  </code></pre>
  <p>I would like the width is 816px, but actually it is 736 (816-50).</p>