Works like magic! Thanks for that.
There are a few other areas where I need to make color adjustments. Some of this can be solved if I switch to the ‘light’ rather than ‘dark’ theme option. However, I still need to change:
background color of the sub navigation of the main menu
background color of the footer area
background color and text color of the footer widget area
If you could let me know what code I need to change for that, it would be most helpful. My experiments thus far have netted me nothing but frustration. 
Just thought: It’s a bit frustrating to have to make these modifications at a css level, rather than as part of the typical customization for the theme…I’m sure there’s a reason for it, but as a person trying to customize a site quickly, it’s not particularly friendly. Having the option of ‘light’ or ‘dark’ with no way to change those particular colors without knowing coding is rather intimidating! I’m not a super coder, I can get by when pointed in the right direction, but having to try and figure out what needs to change where is quite time consuming. I’ve spent hours trying to ‘fix’ this site for my client when it really should have taken me minutes. I hope in some way this can be addressed in the future! In the meantime … thank you for your assistance and patience with my questions.