Real state demo, form validation needed for compulsory elements

Question

Hello,

Thanks a lot for your work for the 4.3 version, it is great and includes valuable additions.

The http://themes.semicolonweb.com/html/canvas/demo-real-estate.html is great. However, how could I include a form validation? For example for the location and property type? rather than let the user to search for anything I would like to have a validation with javascript and do not launch the form unless both inputs have been filled in. I have tried with the validate javascript function from other forms, it blocks the search option, but it does not highlight in red the files to be filled in.

Thanks
Juan