[ShellShock]

You can try the code I posted above in the Calibre Extra CSS field, see if it works. It may not, especially if there is already a p tag in the stylesheet.

I emailed Kobo support about the problem with italics displaying as bold in epubs for some of their fonts, e.g. Kobo Nickel. Their response was essentially I should use kepub instead, as this is their main platform, and the fonts work OK in kepubs. They do not seem interested in fixing the fonts for epubs.