Customize the widgets by adding a custom HTML ID and Class. 
HTML Class: Add the multiple classes with comma (,) separated values. The class can be applied to multiple elements so it could be multiple times on a single page.
HTML ID: Add the ID for the section. The id will be prefixed with “custom-” text. ID is unique on a page and can only apply to at most one element.
For the widget, the classes and id are not directly applied to the widget. It will apply to the div.
Add classes and id without space and if required add valid special characters i.e. [ -, _ ].