Hi everyone! While working on a website for a client, I ran into a roadblock. The client requested a menu bar similar to the one below, but I had having difficulty changing the design to match this (since you can only change the background color for the entire menu - as far as I can tell). So, in addition to the request, this post is going to explain my workaround, just in case anyone else runs into a similar issue.
Initially, I spent hours playing around and trying to find a way to make this happen through the editor’s “design” interface, without any luck. So, I thought, I’ll just set the nav bar to the dark blue background (and use that for “Home” and “Contact Us”), then create buttons (in the colors I needed) and make them link to the correct pages. Until I realized that having buttons covering the nav bar means I can’t access the drop-down menu items. 
My answer to this was to set the background color of the navigation bar to 100% transparent (0% background color), and just put the coloured buttons/boxes behind the now see-through (except for the text) navigation bar. This allows me to still make use of the navigation menu and drop-downs while achieving the design the client requested.
I know this may seem very obvious to some, but I had an unfortunate “brain fart” moment that ended up turning into hours of wasted time. Perhaps my method is the way Wix intends for you to do this kind of customization, but I think it would be a lot quicker and easier if this was available as an option right from the design interface. So, until Wix turns this into an actual feature, I’m posting my solution as well, in hopes that it might help some other poor, lost soul like myself. Cheers!
(Apologies if I’ve posted this in the wrong spot!)