Wordpress default theme code question

[Fonz]

I've started messing with the default theme of wordpress. I figured most of it out but whatever I try I can't seem to get the space on top of page away, I've tried putting topmargin=0 and margintop: 0 px in the stylesheets and regular html code but it just doesn't want to go away. Does anyone know how to do this?

example: www.pornomagnet.com

Thanx