Fix of overlaid modal window

If top is set to 25% on some screens it overlays the page at the very top. As it hidden area - page become unclickable at top of page.

I'm prefer to set top: 100% to avoid this (see attached screenshot):
 
![Screen Shot 2013-04-28 at 3 17 03 AM](https://f.cloud.github.com/assets/1686778/435049/d5a773ea-af90-11e2-8a02-92559fff8cd1.png)