To Customize Template as per your requirement, you can set css for any class from here. If you want to add your css to pricing table or overwrite any default css then you can do that from here in simple way.
Just pick up any class of pricing table where you want do changes and put it in Custom CSS block and save pricing table.
If you will make custom CSS ON, you will get an extra button on each columns on which you will get all css class information for that particular column which will include Column Level Classes, Header Level Classes, Price Level Classes, Body Level Classes, Feature Level Classes, Footer Classes, Button Classes, Ribbon Classes.
Copy class according to your requirements and add into custom css textarea where you will be able to add properties for that class. You will also able to add multiple classes.
There you will be able to have button for Apply To Editor which will apply your css at editor instantly.
Some custom CSS properties may not apply in editor. Please check table Preview for all custom CSS you have applied.