Location: Appearance → Customize → Global → Container
With the ColorMag theme, you can change the visual appearance of the background by changing its color or adding an image. You can set the background color Inside and Outside the container area.
Inside #
It refers to the area where the content is displayed Inside the container area. You can either add the color or images as a background effect. [Available in ColorMag Pro]

Outside #
It refers to the area where the content is displayed Outside the container area. You can either add the color or images as a background effect.
Note: The option will work if you have selected the container width to be a Boxed Layout.

Change Site Background Color/Image