The overlap group sits between two existing groups and covers a portion of those groups. This allows you to break up the linear layout of your page and display content in an appealing and attention-grabbing fashion.
To edit the upward offset, side margins, minimum height, and top padding of an overlap group, simple navigate to the Layout Settings Tab of the Group Settings and adjust the relevant sliders.
Note that when hovering over a group in the editor it will appear above the other groups. In your live site, the overlap group will always be on top.