Originally Posted by grizedale
You would think it would but, sadly, this is not the case. This is the exact method I have been trying to no avail.
Just to confirm, you are opening up the ePub book in Sigil, and changing the "stylesheet.ss" file under the "Styles" folder? The values to be changed are "margin-left" and "margin-right", which were set to 5pt in my ePub books for some reason, so I changed them both to 0 and it worked.