After toying around with the E-book viewer settings I was surprised to see that all the margins were gone, the text fills the complete inner window size. I tried to undo my changes (which weren't margin related at all), but without success.
My last hope was to
restore the defaults. While it deleted all the custom css, search engines, etc. I had previously configured, it didn't solve my problem.
My settings under
Configure E-book viewer > General > Text layout in paged mode:
- Override the page margin settings specified in the book (CHECKED)
- Top Margin: 20px
- Side Margin: 40px
- Bottom Margin: 20px
Thanks for your help!