title: RetinaJS and LESS : Background image doesn't show on iOS
body: <p>I am trying to make a background image into a retina image using <a href="http://lesscss.org/" rel="nofollow">LESS CSS</a> and <a href="http://retinajs.com/" rel="nofollow">RetinaJs</a>:</p>
  
  <p>in my index.html file :</p>
  
  <pre><code>&lt;html&gt;
      &lt;head&gt;
          &lt;meta http-equiv="content-type" content="text/html; charset=UTF-8"&gt;
          &lt;meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=0, minimum-scale=1.0, maximum-scale=1.0"&gt;
          &lt;meta name="apple-mobile-web-app-capable" content="yes"&gt;
          &lt;meta name="apple-mobile-web-app-status-bar-style" content="black"&gt;
          [...]
          &lt;link type="text/css" rel="stylesheet/less" href="resources/css/retina.less"&gt;
          &lt;script type="text/javascript" src="resources/js/less-1.3.0.minjs" &gt;&lt;/script&gt;
          [...]
      &lt;/head&gt;
      &lt;body&gt;
      [...]
          &lt;script type="text/javascript" src="resources/js/retina.js"&gt;&lt;/script&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>in my retina.less file:</p>
  
  <pre><code>.at2x(@path, @w: auto, @h: auto) {
    background-image: url("@{path}");
    @at2x_path: ~`"@{path}".split('.').slice(0, "@{path}".split('.').length - 1).join(".") + "@2x" + "." + "@{path}".split('.')["@{path}".split('.').length - 1]`;
  
    @media all and (-webkit-min-device-pixel-ratio : 1.5) {
      background-image: url("@{at2x_path}");
      background-size: @w @h;
    }  
  }
  
  
  .topMenu {
      .at2x('../../resources/img/topMenuTitle.png');
  }
  </code></pre>
  
  <p>I have both topMenuTitle.png (320px x 40px) and topMenuTitle@2x.png (640px x 80px)  in the same folder.</p>
  
  <p>When test this code:</p>
  
  <ul>
  <li>In Firefox i have the normal Background</li>
  <li>In the XCode iPhone simulator I also have the normal Background</li>
  <li>In the iPhone device, I don't have any background at all.</li>
  <li>I'm using GWT if that matters.</li>
  </ul>
  
  <p>Any suggestions ? Thanks.</p>