There are some books where the
0.2em in this stylesheet modification isn't enough:
Code:
div#book-columns {
padding-left: 0.2em !important;
padding-right: 0.2em !important;
}
I think the most common case would be where the font-size at the paragraph level is set much larger than 1em / 100%. This can happen if you convert the book format with Calibre's "Font Size Rescaling" conversion option enabled, so make sure that option is turned off.
However some publishers used Calibre to create the original book, and so the font-sizes might have been rescaled already. In that case all you can really do is increase the padding in the stylesheet modification above to compensate. 50% increase (0.2em to 0.3em) should be enough in most cases, but sometimes 100% (0.2em to 0.4em) might be needed. I don't know any automatic way to reverse the effects of font size rescaling, and it can be quite a bit of work to do it manually.
(There can be other issues with some books too, such as embedded fonts with highly sloped italics, or the publisher has done something stupid like set negative left/right margins on paragraphs.)