Yes, it can be done thru Calibre conversion. Look at the last 2 posts of the mobileread thread for the answer to your question.
Originally Posted by Ordinaryme
Thanks tomsen for helping me out.
It's kind of awkward, but I don't know how to do change those CSS properties, or where to put these settings/commands. Is this something I have to change in Calibre, while converting the epub..?