[Pros]

When I convert files to epub in Calibre I need to add an extra line to the Styles\style.css (in epub file). I tried adding this line to "Extra CSS" section in "Look & Feel" tab but apparently it's adding the line to html files in epub instead of style.css.

I can manually change style.css with other programs, like Sigil, but I wanted Calibre to do it, each time I'm converting files to epub.