Change color of URL in dropdown menu of Firefox's address bar

I am using a GTK theme with some dark elements, which causes problems in some applications. One of them is Firefox: the URLs in the drop-down menu of the address bar are dark blue on a black background, as in the picture:

How can I change this color, or the background color, without changing my GTK theme? I remember that once was possible to do with the userChrome.css file, but I can't find it again.

I am using Firefox 14.0.1 under Linux.

The solution to this without installing add-ons is to modify userChrome.css.

If userChrome.css doesn't already exist in your profile/chrome/ folder (or if the chrome folder doesn't exist either) you have to create it:

<profile>/chrome/userChrome.css

Then add something like:

.autocomplete-richlistbox {
        background: #808080 !important;
        color: #000000 !important;
}

And restart Firefox.

Based on this answer, installing Stylish and the Firefox fix for Shiki-Colors the problem is solved without needing to tinker with .css files.