Problem with content positioning on different browsers. Please help

Hello, So I have made this website for a customer, please view.

gleamhairstudios

If you see inside the pages (except the home page) on safari you will see all is fine, However on firefox the content box is way off the page.

however the content has a margin-top: -575px; wich I think is well over the top, yet its the only way I can seem to fit it in place on safari.

I really need a solution as this is for a customer, I don’t understand how it can be positioned differently in two different browsers, and dont understand why it needs a massive -margin jsut to get it in place.

Please help, and thank you in advance

Kieran