Injecting Custom CSS Code in Card Forms to change the Submit button style

Hi on the mobile version of the form using the new form builder template my client thinks the submit button doesn't stand out enough is there any way of making this larger and bolder text? 

Unfortunately, there is no way to change the submit button's font size with card forms. However, you may want to change the font-family. This will affect the whole form though.

I hope this helps. Let us know if you have further questions.

nothing that could be done in CSS?
...

Unfortunately, injecting custom CSS code is not possible in card forms. I can forward this to our development team as a feature request if you like. However, we cannot provide any ETA on when will this be available.

We'll await your response.