CSS Works in FireFox but not in Chrome, Opera and IE

Hi there,

I’m building a website using wordpress and buddypress: http://tinyurl.com/4q45s89 , you’ll need a username and password to access it because it’s under maintenance mode, feel free to use those:

Username: sitepointforums
Password: pCx9Ho5WkIyz

My problem is that i came accross some css that works fine in Firefox but in Opera, Chrome and IE don’t.

For example if you check this page http://tinyurl.com/667r8kz in FireFox, this is what you’ll get: http://dl.dropbox.com/u/21335807/infirefox.png

And this is what you get if you visit the same page with Opera, Chrome and IE:

Opera: http://dl.dropbox.com/u/21335807/INOPERA.jpg (The groups are not even clickable here, it seems that there is something else on top of it)

IE: http://dl.dropbox.com/u/21335807/INIE.jpg

Chrome: http://dl.dropbox.com/u/21335807/INChrome.jpg (The groups are not even clickable here, it seems that there is something else on top of it)

It seems that i’m calling the divs wrongly through the stylesheet because in firefox works but in the other browsers it even use wrong bg gor the menu)

The same problem exists also in this pages :

http://tinyurl.com/6hc2nez

http://tinyurl.com/665zbnf

http://tinyurl.com/665zbnf

http://tinyurl.com/69plmav

Any help or advice would be more than welcome, thanks in advance.
-Stelios

Anyone ?