title: Overlapping columns in highchart
body: <p>Is there a way to create overlapping columns?</p>
  
  <p>For example in <a href="http://jsfiddle.net/jugal/67BkD/2/" rel="noreferrer">this jsFiddle</a>, the blue and the red columns should overlap each other as shown below, with the blue being the one at the back and red in front.</p>
  
  <p><img src="https://i.stack.imgur.com/d2d4z.png" alt="Overlapping columns"></p>
  
  <p>To clarify, I don't want stacked columns, both the blue and red columns should start from the xAxis (y=0) and not one over the other</p>