Closing Form Lightbox after submitting Email and Name via form

@russian-dima Thank you so much! It works!

https://www.ayurvedaroom.ch/kochkurse

Is it possible to make a if-function to only make the lightbox close when the costumer filled in all the information into the form?

Else it will close after 3 seconds showing my costumer the “fill form”-error and close the lightbox without sending me the costumer information.