Thanks for the kind feedback!
Yep, it's all CSS. I was lucky...CSS2 came out in browsers just as I was learning about table-based layout. Glad I didn't get too into that, or there'd be some bad habits to break.
As far as the menu flickering, that's a little odd. I'm using Safari v73. The menu should fill in and have a complete border when the mouse hovers over it, but I haven't experienced the flickering...Strange...Maybe it's the new Safari beta? I doubt it, since it's just supposed to fix an SSL problem. But maybe. I don't know if I'm gonna keep the hover effect or not, so we'll see.
The overlapping margins are indeed intended, although some browsers don't get it right. Safari gets it, but so far IE/Mac doens't. It's kind of a subtle detail though, so I don't fret about it. As long as the red text stays above the blue stuff, it should appear as intended.
In fact, it's so good, I'd like to steal it. But then, I know I shouldn't. I just happen to like the way you've put the style together, particularly the headings, and would like to examine the code and see if I could adapt something similar for my webcomic's site.
I really don't mind what you take from the design. There are a lot of variations you could do to make it look significantly different, especially changing the background image (I'm sure you don't want my brother adorning half of your webcomic's pages

). You can also change the colors, borders, etc. But as long as you're learning something, it's fair game.
Thanks again for the feedback!