When using popup builder you might want to show additional checkbox for users to prevent popup showing again.
Title: The text description of the checkbox
Extra class name: If you wish to style particular content element differently, then use this field to add a class name and then refer to it in your css file.
Design option tab:
This tab contains some advanced configs for custom layout, such as padding, margin, typography, custom CSS… Changing values on this tab is not recommended unless you know exactly how its work
For detailed instructions, please go to Responsive Design Options.