Custom Radio Buttons Not Staying Selected

Hello! I’m currently working through some custom radio buttons for a contact form, and I’m unable to figure out how to keep them selected once clicked. I’ve implemented a custom code solution for the hidden radio button itself, using .class-name-here:checked and -.RadioButton_Label to target the visible custom button class, but it’s not working for me.

Here’s my read-only link and here’s the development link.

Here’s a screenshot of the custom code I’ve implemented:

I’ve read multiple forum articles on custom radio buttons, but none of them have any replies/solves.

Any helpful hints on what I’m doing wrong here?

Josiah Z.