title: Margins wont work with auto tag on image
body: <p>Trying to center an image. </p>
  
  <p>Using the <code>margin-left: auto;</code> and <code>margin-right: auto;</code> tags does not work. </p>
  
  <p>Below is my implementation 
  What am I doing wrong / what do I need to add</p>
  
  <pre><code>&lt;style&gt;
  .fix{
      position:fixed;
      bottom:0px;
      width: 30%;
      margin-left: auto;
      margin-right: auto;
   }
  &lt;/style&gt;
  
  &lt;img src="DigitalBannerwithX.png" width="40%" height="auto" class="fix" onclick="this.style.display = 'none'" /&gt; 
  </code></pre>