Hello experts, I'm using odoo 16 enterprise, and I want to show a line or rectangle for all empty fields inside a form, as shown in the attachment (picture) I tried to change some values inside file /odoo/addons/web/static/lib/bootstrap/scss/forms/_validation.scss but nothing happen , Please can anyone help me with that issue regards

Expected some code to solve my problem, hope to show answer clearly with step by step or a picture and I need a result for odoo 16 enterprise version, coding, or by changing some variables