title: Add and remove a class with animation
body: <p>I have written a script that changes the box's color in another box's hover:
  <a href="http://jsfiddle.net/w5b9v/2/" rel="nofollow">http://jsfiddle.net/w5b9v/2/</a></p>
  
  <p>How can I add animation to this transition?
  Thanks in advance</p>