Ah, okay. I thought it might be something similar to how it is with the metadata (where you can use different css for metadata at the beginning of an entry and for metadata at the end of an entry).

Specifying class names and making them change is something you can only do with S2. What we did with metadata was create an option then say if option is A then put metatdata here and use these CSS classes, and if option is B put metadata there and use these other classes.