I use large type sizes in Digital Editions since I suffer from mature eyes. Every fifty pages or so I discover that a sidebar overlaps the text. I can fix that by changing the text size. But I can't easily and quickly REPORT THE BUG.
Presuming that one's generated or written page shown to someone on their own computer will be perfect is the height of arrogance. To avoid that, every such page should have an obvious and easy to use FEEDBACK button. Further, the input you receive from use of the button should be treated with respect and the problems revealed should be fixed. Promptly.