Platform specific font size for labels

Hello,

I'm constructing a cross-platform piece of software (Win/Mac) built around a rather elaborate QWizard. Building my UI, I run into the following issue. On Mac, I want to make a number of informative QLabels smaller than the default font size in order to spare room. Size 11pt looks good next to the default 13pt system font. It turns out that, when running the same UI on Win7, these labels look huge (and ugly) compared to the default 8pt font size. There, I'd like to stick to the default 8pt size.

Is there any simple way to implement this platform-specific font size behaviour at the level of Designer or should I stick to doing the font size modification in software within #ifdef Q_WS_XXX?

TIA,
Antoine