I inserted the code you suggested, but the result didn’t really solve the problem.
First, it appears that the problem is different in each browser. In safari, firefox, and chrome, the initial appearance of the option boxes match the theme color scheme. In IE, the initial color of the option boxes is white. This was true before I inserted the recommended code.
The inserted code at no affect on IE or Chrome
In Firefox, the problem is partially fixed with the inserted code. The dropdown menus in Firefox now look like ladders with the text having a black background immediately beneath. But there is still the light colored background that looks like the ladder. On the checkout page, there was no affect; there the text is still unreadable because of the light colored background.
In safari, the product and cart pages the menus work fine, but the checkout page still has the light background, making text unreadable.