Post background color

Hi!

I could not find this in the documentation or in the settings:

How can I change the background color of posts on the blog page? After switching to the evolve theme all my blogposts have a orange (!) background color. I already clicked the reset options button.

Also how is this setting controlled? I could not find a background color settings in the post editor settings or in the category edit settings. So how can I change the color of posts like in your theme demo ? (some posts have different background colors)