[GeoffR]

I think the book's stylesheet will override the patched device stylesheet, so If the plugin adds padding to div#book-inner in the book's stylesheet then idealy it should choose either left/right padding or top/bottom padding depending on whether the writing direction is horizontal or vertical, or if that is not possible then just add padding to all four sides.

I also wonder if we should add the padding to div#book-columns instead of div#book-inner, so that people can still use the alternative firmware patch that adds padding via the body>* selector? (Some might want to do this if they have a mix of kepubs made with the old and new plugins.)