CSS won’t block a button from submitting unless it happens to be hidden underneath another element. Try removing all the styles from the form to see if it submits and works then.
If it doesn’t then you clearly have a non-CSS coding problem.
Also, the form will NOT submit on CodePen. All form submit requests are blocked there.
As well as this, try using the more standard
<input type="submit"/> for the button instead of
<button>. This won’t change the way the code works, it is just better practice.