I can seemingly fiddle with everything else. However, unless I choose a background picture, I am presented with a Black Background and White Test for the Blogpost Title.
I actually don't even like the "scrolling" interface of blogs, but for now I just want to control the appearance the way "Customize->Change Themes" and "Edit->Customize" does for various Blocks.
I assume there is a CSS/XML or something somewhere. Would seem best if it followed the Themes Setting honestly.