Padding Inside a Floating div | Need Help

I am in the middle of creating a basic, plain jane, old school div layout. But for the life of me, I can't figure out how to get padding in the content area and side menu without the template distorting with extra padding. I've been searching online for hours — and I'm finding 'apparent' solutions, but when I try to implement them, they don't work. I now have a migraine. If anyone has a solution, I'd be rapt to know what it is.

Note: The template isn't complete, per se. I'm just trying…

Padding Inside a Floating div | Need Help