For a local classifieds and forum web site? I may be wrong, but I think you are underestimating her. While my suggestion may sound tongue-in-cheek, psychologists have shown that women have a keener sense of color than their male counterparts. Perhaps you could choose a base color, a shade of brown for example. I’ll bet she could help you select a matching color or colors.
Of course, there is always the risk that she might become a web designer…