Kobo Mini font/line spacing problem

I recently bought a Kobo mini and have noticed problems with books containing hard coded font sizes and line spacing in stylesheet.css.

The mini refuses to change the font size and/or the line spacing. To be expecte perhaps, but the Sony readers and the calibre ebook viewer just pretend they are not there and change at least the font size with no problem.

On the mini the font size will not change and you have big gaps between lines no matter what.

I can get around this by converting to mobi and back to epub, but wondering if there is a better way.

Thanks

Helen