When I open up my profile and see the "summary" questions at the bottom, the only questions with green backgrounds are those with accepted answers. However, in all other views on the site, green backgrounds represent any answers. This question clarifies that the second usage is the intended. Why is the summary tab inconsistent?
I see that in the summary it's the votes that's colored, and on the questions tab it's the number of answers, but it still seems inconsistent to me.
In one, the green background signifies the existence of any answers, in the other, the green background signifies the existence of an accepted answer. Setting aside which is better, these should be consistent with each other. Bart helpfully provided this mockup of a more consistent UI, where the summary tab has the same coloring as the questions tab.