Hello Craig,
PayPlans defines it's own style because not every template has a pricing plan and there is no way for PayPlans to auto-magically adapt to these styles.
I have checked your site and here's what you could do:
1. Take the html codes generated from your Page Builder, and modify the theme file for PayPlans to use those html codes
or
2. A much easier approach is to generate the plans page using your Page Builder and change the destination of the button. This way, once the user clicks on the subscribe, it goes to a different page altogether (similar to going to a payment provide page)