widget css not applying to wp custom fields search plugin

Hello, great work to everybody because I have had great help via this forum.

To increase the search specifics I have used wp custom fields search plugin. Everything is working great except that the widget css doesn't seem to apply to this plugin.

I have tried this plugin on other 2 themes like Transblack 1.0 by AskGraphics and Videotheme and it looks fine with those themes but not for when I use atahualpa.

Using atahualpa 3.5.3, wordpress 3.0.1

Any pointers? thanks.