[asicsp]

Foliate works great for reading fiction. Customization for theme, font, etc, were nice.

I use Atril Document Viewer for technical epubs though - feels much like viewing a PDF.

[ObscureScience]

I got kind of annoyed that the headings are not part of the color schemes, and for me they always stay dark red, which is pretty unreadable in dark themes and looks bad in many light ones.

Using the flatpak version.

[asicsp]

I'd suggest opening an issue, post some screenshots and indicate what might help your case.