Google is testing using colors for the +topic search bar refinements, those bubble buttons you sometimes get under this search bar in Google Search. I see normal white buttons, then grey, blue and green, but I am sure there are more.
This was spotted by Ethan Lazuk who informed me of this on Twitter but I can replicate it in some mobile browsers (not all) and here are the various colors I saw. You can click on the images to enlarge, if you like:
This was not in the SGE interface for me, but I do wonder if Google is trying to get the topic in design sync with each other?
I am not sure if I like it or not.
Forum discussion at Twitter.