title: Why ":last" and ":last-child" does not work?
body: <p>I'm trying to select the last div with class <code>my_class</code> inside div with id <code>a</code>.<br />
  I tried several options with <code>:last</code> and <code>:last-child</code> but none of them worked.<br />
  <a href="http://jsfiddle.net/eU7By/2/" rel="nofollow noreferrer">Here is on try.</a></p>
  
  <p>What am I doing wrong ?</p>