It's part of the move over to the hovercards / pop up user info that was suggested. If the green looks bad for everyone we can alter that. Hopefully some further customisation will be possible in the future.
If you still don't see the pop up bit appearing let me know. Possibly you just need to clear the browser cache for the site to make sure you are updated.
If this post is irrelevant to the topic please ignore it.
It may be a test and it may be deleted shortly.