What is the "CSS id" at the widgets, and how do I use it?

At every of the custom widgets, you will see a field named “CSS id”

Let’s say that you are using the widget that outputs the contact form section at your homepage. Let’s also say that you give this widget the CSS id:  contact.

Now if you want to have a “contact” menu link at your top navigation that will slide down to the contact section when clicked, then you will use the CSS id that you just gave to your widget, as a link to the menu item (make sure you add a "#" prefix). In our case as a link for this menu item you should use :