Cannot create Background Picture for Node which has Children

Hi,

I am trying to create custom formatting for nice menus. As a theme I am using Mayo. What I am trying to do is to put a background using the background picture approach:

background-image:url('../green_bar.jpg');
background-repeat:repeat-x;

I am able to have it work (shows up in browser) for the following components:

• .block-nice-menus
• ul.nice-menu a

however I am unable to make it work for .

The reason is that there are specific references to that field in two other css files:

• sites/all/themes/mayo/css/style.css
• sites/{site}/files/color/mayo-696b8ffc/colors.css

Is there a way for nice menus to NOT write out CSS into those two files?

I appreciate your response,

Rene