Change dropdown menu colors in coursepress pro theme

I've tried what's suggested here:
https://premium.wpmudev.org/forums/topic/how-do-i-change-the-colour-of-the-background-of-the-dropdown-on-the-menu

Made absolutely no change in our theme at all. I found the main-navigation identifier in style.css and edited what I believe is accurate, but that made no change whatsoever as well. In firebug, the change took place immediately, but I've cleared cache and even attempted to view the site in an alternate browser with no effect. I feel like I'm editing the entirely wrong theme or something, because no matter what I change, I'm seeing nothing, even after I clear cache and restart browser. Any insight is much appreciated. All I want to do is edit the theme to have a different dropdown background and link color. Support access has been granted in case it's needed.

Site is here: http://course.changeyourlifewiththelaws.com/course/change-your-life-with-the-laws/units/day-1/page/1#unit-page-1

Thank you.