title: use transition on ::-webkit-scrollbar?
body: <p>is it possible to use transitions on webkit scrollbars?
  I tried:</p>
  
  <pre><code>div#main::-webkit-scrollbar-thumb {
      background: rgba(255,204,102,0.25);
      -webkit-transition: background 1s;
      transition: background 1s;
  }
  
  div#main:hover::-webkit-scrollbar-thumb {
      background: rgba(255,204,102,1);
  }
  </code></pre>
  
  <p>but it isn't working.
  Or is it possible to create a similar effect (without javascript)?</p>
  
  <p><a href="http://jsfiddle.net/Cjj6v/">Here is a jsfiddle showing the rgba transition problem</a></p>