IE7 menu display issue

Hi

I have an issue with a menu displaying correctly in IE7.
In IE8 and FF the menus display correctly including the sub-menus.

In IE7 there is suddenly a white background showing, not allowing the menu-bg gradient to show through.

Is there a way to set the IE7 errors without having to add a if you get IE7 then do this style sheet.

The url is: https://www.topfruit.co.za/news.

Thanks very much for any help or advice.