title: How do I get just the x or y position of the background image using prototype?
body: <p>Hey, I'm making a simple user friendly css editor using Prototype. Anyway, I was wondering whether I could get the background-position x/y values on their own?</p>
  
  <p>I wish I could do something like this but sadly it doesn't work:
  <code>element.getStyle('background-position-x);</code></p>
  
  <p>I guess this is because position comes in different forms like 'center' rather than just being generic.</p>