[hardvice]

I'm in the process of converting a bunch of MOBI .PRC books to .EPUB. The original html files from which I built the MOBI files (using Mobipocket Creator) use relative font sizes in the CSS. For example, the CSS class for the book title uses font-size: x-large; while the class for chapter titles uses font-size: large;.

When I convert the MOBI books in Calibre, everything comes out as normal-sized text. If I open the .EPUB book in Sigil, it appears all of the classes of different sizes are being combined as class=calibre4.

I can edit the books in Sigil to restore the relative font sizes, but it's obviously a pain.

It seems like the font size rescaling in the Look & Feel page during conversion should take care of this, but it's not. None of the source files contain any explicit (i.e. point-size) font size declarations; they use font-size: normal; for body text instead, and I'm guessing that's the problem.

If I use the font size rescaling in Calibre (currently set as base font size 12.0 and font size key 5.0, 7.0, 9.0, 12.0, 13.5, 17.0, 20.0, 22.0, 24.0), I get the same result--all text is the same size. If I explicitly disable font size rescaling, I get the same results.

I'm currently using the Default Input Profile and the iPad output profile.

Is there anything I can change during the conversion to preserve these font sizes? I'm converting a couple hundred files, so anything I can do in Calibre would be preferred to editing all the input or output files manually.

Thanks in advance.