I have searched and could not find this posted but, if so, feel free to delete this post:
I have for sometime been bothered by the Google Toolbar making my form field content yellow. Well, If you will add background-color: #000000 !important; to your css class assigned to this element, the problem is resolved. The hex value of your background is of course dependent upon your site. “It Works”.
Like I say, If this has been posted elsewhere, just delete this post moderator!