I think I have figured out at least some of the CSS I need for improving lead capture pages. I am still a bit hesitant, though, as I fear I might mess with the functionality as I style things--I don't want to build a beautiful page only to have it accidentally lead nowhere.
Right now the thing I haven't yet got straight is margins v. padding settings. I may give it a rest and resume tomorrow. My pages at least look a little better today than yesterday, so there is progress. Here is what they look like today: