fixed the problems
ie 6 was running in standards mode and FF in border-box model.
That caused the reversed diference. Bit strange to have it like that, didn't really think of that.
Another problem was coming from the ie float and margin double margin error
And another problem was caused by clear:both
Which firefox (correctly) caused the content to go beneath the left bar, which also contains a float. Had to fix that by doing a float: left width:100% ugly solution
P.s. is that css website from the same makers as this website???