Sorry to keep coming back to this thread, but so far this is the only place I've found discussing themes in a remotely helpful way.
What are you using to generate the CSS file from the two SCSS files?
I copied the lightly theme and updated/added a couple of variables. I then used bootstrap.build to generate the CSS file, but it breaks the layout (see screenshot). Is there some other way to generate the CSS? Surely you aren't editing it by hand, are you?
OK, thanks for the input. My theory at the moment is that Lemmy doesn't actually need the SCSS files. If you look at the CSS file, it doesn't reference the variables at all. That's why you've had success modifying the CSS by hand. Somebody in the Matrix chat said that they pulled down the
lemmy-ui
code so that they could generate the CSS file in the same way that the built-in themes do. I'm going to take a look at that now and see if there's a way to extract that portion.