title: CSS centering of an image not working
body: <p>I'm trying to center an image (forces.png) horizontally using margin-left and margin-right auto but the image remains left-aligned. My site is <a href="http://goo.gl/cHO1u" rel="nofollow">http://goo.gl/cHO1u</a>
  What's wrong with the code I'm using? Thanks</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;div class="section" id="presentation"&gt;
  &lt;div id="presentation-highlevel"&gt;
  &lt;p&gt;NOTRE ENTREPRISE&lt;/p&gt;
  &lt;p&gt;ddfdsfdsfdsfdsjfl dfljdsfdsfjdsjfdlksj dfljdslfjldsjflkdsjflsjfdls ldf,dlsmjfdsjfsdmfjdmsjfms dfmdsfjmdsjfmdsjfmdsjfdlms mkdfmksdmfkdmsfkdsfdsmfkmldskf dfmdmkfmdkfmdlskf dfkdmfkdmkfmdskf dfmkdsmfkdsmkfmdskfdms dskfdsmkfdsmkfmdsfkd &lt;/p&gt;
  &lt;/div&gt;
  &lt;div id="presentation-highlights"&gt;&lt;img src="images/forces.png" alt="Picture" /&gt;&lt;/div&gt;
  &lt;/div&gt;&lt;!--END page1--&gt;
  </code></pre>
  
  <p>CSS:</p>
  
  <pre><code>#presentation
  {
      height:1300px;
      background:#afc9ff; 
    background: url(../images/norway-landscape60.jpg) no-repeat center fixed; 
    -webkit-background-size: cover; /* pour Chrome et Safari */
    -moz-background-size: cover; /* pour Firefox */
    -o-background-size: cover; /* pour Opera */
    background-size: cover; /* version standardisée */
  }
  
  #presentation-highlights
  
  {
  width: 100%;
  display: block;
  margin-left:auto;
  margin-right:auto;
  }
  </code></pre>