Confirmed by Google, it is now testing a core search results user interface design. With this test, it includes a rounded search bar at the top, a smaller Google logo. A really noticeable attribute is the search bar header that sticks to the top as a user scrolls through the results.
This was first spotted in a Reddit thread and Google confirmed this is one of its many tests. A Google spokesperson said “We’re always experimenting with new ways to improve the Search experience for our users.”
Here is another screen shot from the Reddit thread:
At this point, I was unable to replicate this test myself.