Need css to fix the look of the pro sites check out page

Hi there, I need some css to fix the look of the pro sites checkout page. I am using the spirit theme and the check out page looks squished and without boxes for input of credit card number etc…. When I switch themes (twenty sixteen) the same page where one inputs the credit card information looks great! Spirit….not so good. See screen shot. I would like boxes at least to show the user where to input their information. I am pretty sure the css code that I would enter in my theme's custom css would begin with

div#psts-checkout-output but not sure if that is correct and what the rest of it would be.