I am using rich:contextMenu and want to style the background of the right (smaller) side
(in which icons can be placed, the standard-background is blue).

But I cannot find the proper css-class for that.

I tried it with:
- rich-menu-list-border,
- rich-menu-list-bg,
- rich-menu-list-strut.

This adds a background to the left side of the menu:

.rich-menu-list-bg {background: url(...) 0 0 repeat;}

This adds a background to the whole contextMenu (left and right side):

.dr-menu-list-bg {
background: url(...) 0 0 repeat;
}

But I only want to change the background of the left side of the contextMenu.

What css-class I should use?