Color the top 15% of a LaTeX background in a particular color?

I have seen documentation on how to use the wallpaper package to put an image on the background, but I am looking for a simple solution 开发者_如何学编程to color the top 15% (or so) of a page in some color. How can I give part of the background of an output page a color with LaTeX?

Perhaps you can use PGF/TikZ to create such a colored bar at the top of your page?