Appointmets + button size for paypal link

Hello! I have appointments plus and once you go through the booking form and then click to ‘confirm the appointment’ a button appears in the bottom right of the page directing the user to paypal for payment.

I want to make this button central on the page, bigger and if possible a different colour as at the moment its white background blends in with my site. Making it hard in my opinion for the users to see.

Here is a link to the page if it helps

Is there a way to do this?

Thank you for your help and also the great plugins you continue to produce.