Found a toggle menu example at Shay Howe's site (learn.shayhowe.com). Trying to incorporate into my mobile design, but so far I've had to move my nav box out of the header, which will cause design problems when I want my menu to be within the header on larger screens. I'll also look for other versions of toggle menus, since I heard that you can use JS or jQuery rather than CSS to make them work. That would hopefully allow me to put my nav div box back inside the header where I want it.
Created navicon for main menu's dropdown in mobile design. Tried adding some copied javascript to hide or show those menu items depending on screen size, but the script still needs work. Created new media query to hide the navicon at screen widths above 800px, when regular menu will be visible again. Fiddled with the CSS terminology for background colors and images of the footer's social media background until I got the mix-width/max-width mix-up straightened out. But still cannot display desired background image at screen widths above 400px. Reorganized CSS pertaining to link display, but still can't display dividing lines in sitemap links, and can't make the navicon link change color in hover/active/focus states.