Adding classes to inputs and labels in Umbraco Forms

Thank you for that idea Chriztian! That may be what we are going to try first, my only question is we are using the latest Umbraco 15 but going to that themes page I only see a default for 14, would I be running into any issues using the default theme for Umbraco Forms 14 when I have Umbraco 15?

Hoping to find some tutorials that implements what we need.