In this subsection of the theme customization panel, you can set a color or an image for the form page background. The image can be linked to or uploaded from your computer. The page background can also be transparent.

The next options refer to form frame, rounded corners and box title, which can all be set on and off. Select a color for the box title and specify whether the headline will be placed inside or below the box title.

Finally, set the form background color (it is different than the page background color) and turn the frame shadows on or off.