Mootools Firefox problem

Hi All, hope someone could point me in the right direction,

I am using mootools (latest full version) i am using it to do two things, one to change the colour of the links which works fine the other it to reveal a hidden contact form, it works perfectly in ie7-8 but firefox and safari its very broken.
Hers the link
http://www.web-fox.co.uk/demo/form/untitled.html

i think its probabley a css problem but not sure.

many thanks.

Or an easiery question, does anyone know how to create the text fade (as per link above) with jquery as i can get the form working with that?

I think i know what the problem is but dont know why it is happening, mootools fx.slide seems to creat a div around the content that needs to be toggled from hidden to visible, but with safari/firefox the height valeus changes but the hidden value doesnt toggle any ideas!?