What's Better? AZW3 or KFX

[theducks]

Originally Posted by MrSlow&Steady

So there’s a way to fix the problem I already mentioned? And how so?

Fix the code. It ain't rocket science.
There is no One Code to rule them all. You need to trace the code affecting the bad item.
Both Calibre and Sigil are EPUB editors.
They have a Jump to link or style functionality, that usually takes you right to the piece of CSS that is being used.

CSS typically sets Margins, font face and size, indent
The average novel is pretty basic HTML /CSS

It is the fixed layout books that get trickier, because you now control everything.