title: CSS "width: auto" is not working on <div>
body: <p>I want <code>.test_info</code> be width auto, not the same as the width of <code>#test</code>.</p>
  
  <p><a href="https://jsfiddle.net/ef6ukobf/" rel="noreferrer">https://jsfiddle.net/ef6ukobf/</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>#test {
    background: #26A65B;
    height: 30px;
    width: auto;
    margin-top: -8px;
    margin-left: -8px;
    margin-right: -8px;
  }
  .test_info {
    background: #00ff00;
    border-radius: 5px;
    height: 20px;
    width: auto;
    margin-top: -2px;
    margin-left: 20px;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div id="test"&gt;
    &lt;div class="test_info"&gt;50&lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>