Cant make font on pages uniform

Hai,
For some reason I can't get the font the same on my pages. I want the bodytext average sans, but on this page: http://dawsonvastgoed.nl/dutch/langevelderlaan-2/ I still have arial.
Has this something to do with my custom css? Could you look for me? I permitted access and already spoke to Rupok about this...Thanx!