I suppose that would work if the device just overrides the base class. I was thinking it just ignores the css sheet altogether. If .para is defined on the sheet, and the sheet is ignored, then it would ignore the .para as well. If I were a developer it seems like it would be easier to just give the user selected setting - like margin, font-size, etc. - an !important tag to override just those parts of the base tag.
Oh well. Thanks for the brain exercise!