title: Width transitions on ::after pseudo-element not working in Edge
body: <p>I'm using CSS transitions on the <code>::after</code> pseudo-element and it's working perfectly fine in Chrome and Firefox; however, it's not working as expected in Edge. The background color transition is working on the pseudo-element, but the width isn't.</p>
  
  <p>Here's my current code: <a href="http://codepen.io/anon/pen/ZbYKwv?editors=110" rel="noreferrer">http://codepen.io/anon/pen/ZbYKwv?editors=110</a></p>
  
  <p>For the purpose of being able to see the transition clearly, I increased the duration from 400 ms to 4000 ms. I also added a white background to the <code>&lt;label&gt;</code> because Edge doesn't seam to support a data URI SVG for a background image (I'm actually using a file, but I can't upload that to CodePen).</p>
  
  <p>So what can I do to make the width of the pseudo-element animate as expected on Edge?</p>