How to edit CSS buttons in the checkout pages?

Hi guys,

I'm using CSS buttons on my store (https://www.jollyrogerbay.it) and they works very well. I had changed the "Buy" css button (that is 'Acquista) in the product page succesfully (it's orange and bigger than other css buttons) as you can see here:

http://www.jollyrogerbay.it/store/giochi-nuovi-sparatutto-c-33_42_44/halo-the-master-chief-collection-xbox-one

But I can't do the same for the "Forward" css button in the Checkout_shipping page (and in the following checkout_payment and checkout_confirmation pages), I've tried to edit lots of file with the style commands that I need to use, but no effect is shown on the site, the only thing I had been able to to was to move the Forward CSS button on the left instead the original position on the right.

What can I to in order to stylize this buttons differently from the other buttons?

Thanks in advance

Marco