title: Style webkit scrollbar on certain state
body: <p>I'd like my <a href="http://www.webkit.org/blog/363/styling-scrollbars/" rel="noreferrer">WebKit scrollbars</a> to have a different color when its container is hovered over. I want the entire scrollbar to light up.</p>
  
  <p>I was thinking something like this would do the trick (but it doesn't):</p>
  
  <pre><code>.scroller:hover::-webkit-scrollbar {
    background: green;
  }
  </code></pre>
  
  <p>I've styled the scrollbars the same way: on <code>.scroller</code>, not globally. (That works: <code>.scroller::-webkit-scrollbar</code>) I want the overflowed divs special, not the document.</p>
  
  <p>Another (related) problem: light up the thumb when hovering over the scrollbar. This doesn't work:</p>
  
  <pre><code>.scroller::-webkit-scrollbar:hover ::-webkit-scrollbar-thumb
  </code></pre>