If you find the ID of the stack in the inspector then you can target that. Or you could use the new custom class option if you are using S4.
e.g. the ID of your grey background is #stacks_in_631503_page1 so you could just set a different background colour for that.
A simpler way that works quite well I have found is to use a largely transparent colour (instead of a solid colour) as this same colour often works well across both modes.