title: bootstrap3 media object <div class="media"> not works
body: <p>Follow the instruction at <a href="http://getbootstrap.com/components/#media" rel="nofollow">http://getbootstrap.com/components/#media</a>, I copied the code: </p>
  
  <pre><code>&lt;div class="container"&gt;
  &lt;div class="media"&gt;
        &lt;a class="media-left media-bottom" href="#"&gt;
          &lt;img src="https://www.gravatar.com/avatar/16250bf5bb2c9f970cdc0f43c830b34f?s=32&amp;d=identicon&amp;r=PG"&gt;
        &lt;/a&gt;
        &lt;div class="media-body"&gt;
          &lt;h4 class="media-heading"&gt;Bottom aligned media&lt;/h4&gt;
          &lt;p&gt;Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin commodo. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.&lt;/p&gt;
          &lt;p&gt;Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu leo. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.&lt;/p&gt;
        &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>at jsfiddle <a href="http://jsfiddle.net/x3a1c40h/3/" rel="nofollow">http://jsfiddle.net/x3a1c40h/3/</a></p>
  
  <p>As we can see the img appears on the top of the text, but not on the left, why is that?</p>
  
  <p>Thank you!</p>