Mailing List Hover Click Color

Hello I am the webmaster of http://www.houstonjapanfest.org at the bottom of our page we have a mailing list sign up powered by Vertical Response with embedded code, it works perfectly expect for the fact it generates a light yellow color when you click and hover over it which makes the text hard to see since it is white. The code that does this is in the embedded code which sadly cannot be edited. Is there a way to over ride this code or at the very least change the text color to black? I really just want this for the mailing list embedded code. Any suggestions or advice even for a better mailing list that can be more customized is also welcome. Thank you so much