title: flip effect not working in mozilla
body: <p>flipping effect is working perfectly in chrome but its not working in Mozilla
  please check this fiddle <a href="http://jsfiddle.net/asomani/kr4s4k7f/4/" rel="nofollow">http://jsfiddle.net/asomani/kr4s4k7f/4/</a></p>
  
  <pre><code>&lt;div class="stage"&gt;
      &lt;div class="flashcard"&gt;
          &lt;div class="front"&gt;
              &lt;p&gt;1&lt;/p&gt;
          &lt;/div&gt;
          &lt;div class="back"&gt;
              &lt;p&gt;2&lt;/p&gt;
          &lt;/div&gt;
      &lt;/div&gt;  
  &lt;/div&gt;
  </code></pre>