Originally Posted by taming
In general, the margin control issues have been related to calibre formatted or user formatted books--not kepubs or ePUBs with their original style sheets (with or without DRM)
To be a little picky...
It isn't really a calibre thing. It is whether margins are set in the stylesheet of the epub. The margins are the @page margins and possible one other type.
The reason that calibre gets blamed is that its default format conversion options set them. The size of the margins could always be adjusted, but the ability to not set margins at all was added a few months ago.