Looks like Yahoo is now experimenting with their own background colors for search ads. Spotted by @tecnonetblog – Yahoo seems to be testing a green background color for their ads. Personally, I see a light blue colored background for Yahoo ads.

Here are screen shots of the test.

Green Background Yahoo Search Ads Test:

Blue Backgrounds Yahoo Search Ads:

Google is frequently testing different colors and shades of backgrounds for their search ads, so this should come as no surprise.

Forum discussion at Twitter.