So I've found a decent solution for this problem!

I have changed my Admin->Config->Layout Settings-> Column Right Status Global to 0 so there is never a right column. (Never use it and it made my site center column a little larger and easier to view....so very good improvement)

I then separated out #navSuppWrapper on line 49 of stylesheet_colors.css and set the background color from #333 to #FFFFFF and it worked! I now have changed this large background charcoal color to white so the site is legible and displays the same now on desktop, phone and tablet views.

The only small change that it affected, was now when you look at the footer, the previous view showed it as a charcoal bar with white writing. It is now a white bar with white writing.....but I can live with this as the pages it directs customers to are all in the main nav bar at the top of the site anyhow.

Thank you once again mc12345678 and simon1066 for your help and working through this....it helped to solve this!