Simple Tree Menu not working on Firefox

[ruks12]

1) Script Title: :: Simple Tree Menu

2) Script URL (on DD): http://www.dynamicdrive.com/dynamicindex1/navigate1.htm

3) Describe problem:

Hi,

I have added the script to my website, on IE it works fine but on Firefox 4 it doesn't work at all, the css does not work

here is the link i have used the code http://www.solfex.co.uk/products.htm

Please can you check on Firefox and let me know what i need to do

Thanks

Ruksana