Custom Error Notifications for Required Fields

Hello,
I’m hoping that the community could help me out with an issue I’m running into with one of my Landing Pages. The landing page is using a form with a Yes/No question in it, but due to the limited customization in the Unbounce builder I am using some custom CSS to style the “Yes/No” radio buttons to look more like buttons on the live page. These are required fields in the form and if a user doesn’t select one they cannot submit the form, however, due to my CSS if you do not select a radio button the error message “Required Field” does not appear anymore…

My question would be if anyone has a solution or an idea that I could implement where an error message would appear if the radio button is not selected?

I’m attaching a link to a test page that is having this issue if you’d like a visual. You’ll notice that if you do not choose a yes or no answer that it doesn’t necessarily let you know that the yes/no question is a required question. I would like to find a solution to that, but I’ve spun my gears looking for answers and I’m hoping someone could chime in with some insight!

TEST PAGE LINK: http://unbouncepages.com/test-page21/

Thank you in advance!