Add Class to Button

So it looks like this plugin is wrapping a “div” tag around the “form” element. I don’t see anywhere that I can set a class on that div or on the form itself. Seeing as that div is set to “display: block” I need to change this. I have other div in the main container so just targeting divs or by children is not an option as the orders can fluxuate.

How do I assign a class to the button?

The page I need help with: [log in to see the link]