i use em exclusively in all my ubbt 711 styles and the classes inside of the body follow with relative sizes determined by the body's em value.
eric meyer has some excellent examples of 100% em solutions and why to use them.
An example that's an old one, but it still applies. he mentions the 'containing div' . well the body is the ultimate containing div, so it causes all to follow.
once again, it's STILL a personal choice and i only offer it as what i prefer.
using pt and px work too. it's just more work from where i see it.
ps: i'm not 100% em. just only for fonts. i use px where size matters and for absolute/relative positioning and width,height etc.
