Baz,
Two possibilities seem most doable:
1. Use that background, but have it repeat only vertically, i.e remove that right partial and use that background color as fill.
http://www.practiceboard.com/?10185142
2. The other is to completely replace background and the ghosts with a solid (#e6e6e6 for test):
http://www.practiceboard.com/?10185149
Danno
Edit: Here's a little darker gray with a blue added (#c5c5ca).
http://www.practiceboard.com/?10185158