As someone pointed out during James Weawer's presentation, the default CSS does not match those of Swing or the underlying OS (the participant mentionned Windows especially).
When asked, Jonathan Giles indicated that those were not supportée in the current 2.0 release, of course.

It would be good if those styles were considered for inclusion as alternate style sets in a future release. Not having the option to use those common styles make a lot af additionnal work for the developer to re-create those styles if he wants to integrate his FX components to his Swing app or to make it look like a Windows app.