problem with whmcs integration

I have issues with whmcs integration and firefox, take a look at the following captures and how i see WHMCS form using chrome:
https://www.evernote.com/shard/s262/sh/2cfcedde-ca33-446f-b164-61dcce40f975/704f571e15efc2957b8a1baf17aea174/deep/0/Mi-Cuenta---AMITOSAI---Online-Marketing-&-Hosting-y-WordPress-Help-Forum---The-WPMU-DEV-Community.png

Now check how it looks on firefox:
https://www.evernote.com/shard/s262/sh/020b1d65-d23d-46d0-936c-4db4cb2eafcd/722b932db9855f2b3ce0707074aceff3/deep/0/Mi-Cuenta---AMITOSAI---Online-Marketing-&-Hosting.png

Also you can try yourself with th following url:

http://www.amitosai.com/mi-cuenta/clientes/submitticket.php/?step=2&deptid=6