MMW4 on Windows 11 and skin issue

[duh FooL]

I got a new PC and like an idiot, forgot to migrate MMW4 from my old one.

Brand new install, etc.

I installed some skins, but I see a weird problem where the background of the window (especially in things like lists, etc) is dark.
It doesn't look like the picture of the skin that one the Skin download page.

For example, CleanMM 1.0.1, the Options window shows up with dark text on a dark background.

Ignore the error message, because the colour scheme occurs even when there is no crash.

Is there some setting I need to change, either in MMW4 or Windows 11?

Previously, I was running on Windows 10.