It is possible to add background images for the main menu by adding them here:
Project Settings > Menu settings > Menu background image
and the same is true to pages here:
Page Settings > Theme settings > Page background image
Isn't it be possible to add a background image to submenus? Submenus has the same settings as pages and thus has the "Page background image"-setting, but these images don't show on a submenu.
Framework: 5.16.0
AT: 0.10.5
/Henrik