title: highcharts tooltip z-index
body: <p>I'm trying to get the highcharts tooltip to have a zIndex using <code>useHTML</code> to position it over another HTML element.</p>
  
  <p>See this fiddle: <a href="http://jsfiddle.net/sDu8V/" rel="noreferrer">http://jsfiddle.net/sDu8V/</a></p>
  
  <p>I'd like the tooltip to go over the pink box - instead of under it.</p>
  
  <p>What am I missing?</p>