Composer/Background
From DS Help
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There are 3 ways to configure the background. Either by using a solid colour, an image or a theme.
The solid colour and the image are self explanatory.
In version 4, Theme was introduced. In a theme you choose a background image and then apply a layout to that image. That allows more flexibility as it's possible to add any layout to any image and there is no longer a limitation with image/layout combination.
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