I've just been nosey-ing at someones css and his sizes are in em and not pixels
could somebody please explain what em's are and tell me the conversion rate into pixels.
i would be most grateful.
Thankyou!

em is the actual font size, theoretically this is the proper way but most people use pixels.

Explination one em is equal to the current font size of the current element

More info (http://www.bigbaer.com/css_tutorials/css_font_size.htm)