We recommend to have both!
Background Image : The image you upload here will become the "wallpaper" of your campaign when the user's screen is the same size as the image uploaded and defined in the "Look and Feel" tab. We have set it up at 810px wide by default but you can of course choose other values.
Banner : The image you upload here will be displayed :
- always if no background image has been uploaded, OR
- when the screen is smaller than the width specified in the tab 2 "Look and Feel" (810 px by default). The background color will then appear in the background of your campaign.
In summary, in most cases the background image is visible on desktop & is replaced by the banner in mobile environment to make sure all user's have a perfect accessibility to your campaigns.
We recommend to make sure that your banner & background image have the same look and feel to ensure consistency between the desktop and mobile display of your campaign.
You have uploaded a background image of 810px wide
A banner of 810 px wide
and a background color : white
=> If the user's screen is of 810 px : the background image will be displayed - your campaign will look as follows :
=> If, the user's screen is smaller than 810 px OR no background image would have been uploaded
then the banner and background color will be displayed - your campaign will look as follows :