Add class to required fields

I’ve just added this to the next version: https://github.com/mikejolley/WP-Job-Manager/commit/cb52965dd3c43ef36a46511b4b342160bc891603

All required fields will be wrapped in a div with class required-field. That should be enough to write some jquery code which loops each required-field, checks the value, and then either adds another class or some other visual cue. That part would be down to you.