Optical Illusions

Bored? I love optical illusions... this one really tripped me out - I still can't see it right... the 'A' & 'B' squares are the same color. Don't believe me? Save the pic and open it in Paint or snag the two areas and open them up elsewhere. WTF! Right?
http://www.skytopia.com/project/illusion/illusion.html