Originally Posted by JeremyR
Yeah, but it's really a Calibre specific epub issue, though. The margins seem to look fine when the epub is viewed as an epub.
An epub is an epub, if you want to remove margins you need epub advice. Personally epubs with a main left and right margin of 1em doesn't look great on any ereader unless you use the smallest font the larger you scale the font the bigger the margins become. Viewed on a computer or large screen it is ok but publishers seem to think we like them.