Possible Duplicate:
Why are some questions on the question page darker than others?
I've really tried to figure this one out on my own, but I give up. What determines whether or not a question is shaded with a green-tint background on the ALL QUESTIONS pages? I'm just hoping it's not something obvious.
A question is shaded green if one of its tags is in your "Favorite Tags" list on the right column of the page.
This is highlighting questions with tags that are in your favorite tags. If you haven't manually added any favorite tags, the system will detect when you have a certain level of activity in a tag and infer one for you. If you manually add a favorite tag, the system will not infer a tag for you.
You can customize your favorite (and ignored tags) in your profile. You can also customize these settings in the right sidebar of the homepage and the /questions listing.
If the system is inferring a favorite tag for you and you would prefer not to have any questions highlighted, you can simply add a nonsense "tag" to your favorites. Perhaps unicorns-eating-waffles? (:
