I've given up on reading epubs on my computer. All epub readers are crap: inappropiate fonts, weird spacing, no sheet margins (like the ones pdf readers have), etc. PDFs, on the other hand, look nice 95% of the time, unless someone uses calibre to convert an epub to pdf.
Have you tried Thorium? https://www.edrlab.org/software/thorium-reader/
What an excellent little tool! Thanks for suggesting this.
I've settled for an epub reader (after testing many others) with which I'm not entirely happy: https://icecreamapps.com/Ebook-Reader/
Thorium Reader looks very promising.