title: Defining overflow direction of vertically aligned flexbox item
body: <p>I have a flexbox with a single item. This item is horizontally and vertically centered. When the item grows taller than its container it overflows equally at the top and the bottom of the container. I would like it to only overflow at the bottom, and remain anchored at the top. Any ideas?</p>
  
  <p><a href="http://codepen.io/wilsonpage/pen/LzryK" rel="nofollow">http://codepen.io/wilsonpage/pen/LzryK</a> (view in Chrome Canary for latest Flexbox)</p>