Google is testing another user interface for the topics refinements we saw them testing a few months ago. This new layout and design was spotted by Paul Shaprio and posted on Twitter.
Here is an animated GIF of the topic refinements working, as you click on them, it toggles the search results based on your selection:

Paul Shaprio said “the button click animates between result variants without leaving the SERP.” “Really nifty,” he added and I agree.
Here is a video of it in action:

Check it out! pic.twitter.com/mXh9I52lcY
— Dan Plante (@Dan819) October 4, 2017
This is what it looked like before:

I still cannot replicate this myself.
Forum discussion at Twitter.

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