Any thoughts or solutions?
Well the above answer didn't quite work I am not sure why. I fiddled some more with floating the button and putting it in other divs but that didn't work.
What I ended up doing is putting one dummy div in between the growing. I just it to a height of 1px and then gave the div beneath it a margin-top -1px. I hate work arounds but it does work.
Probably it has to do with the positioning relative the pharagraph containing the Login link. try moving the link inside the div id logoWrapper and float it to the right. This way you will also have less markup!