I'm designing an ebook. Finished product will be in PDF. With ebooks, as you know, some users like to read online and others prefer to print them and read. Therefore, I want to select fonts for my section titles and body text that work well for both online AND print reading. Everytime I think I've found a good combination that looks great online and is easy to read, ends up being not very easy to read in print (and vice versa). What are your recommendations?