Depends on the jurisdiction, and the law being broken. Standard Caveat: Not a lawyer. Also this is based on US Law. This isn't the game itself, just the Game

Depends on the jurisdiction, and the law being broken. Standard Caveat: Not a lawyer. Also this is based on US Law. This isn't the game itself, just the Game UI recreated in Webflow. So while it doesn't recreate the game per-se, it does use image assets which are likely copyrighted by Firaxis. In my limited legal understanding--assuming the author did not first seek permission to use game assets, the author could claim defense by Fair Use doctrine, that allows copyrighted materials to be used in limited cases. For example using a short clip from a movie as part of a movie review, or an excerpt from a book in a book report. In this case, the author could claim the images were used to teach people how to use Webflow, but again my limited legal opinion is that Firaxis could counter that claim by pointing out the author isn't a teacher, and this is not part of any sort of educational series. The author could instead claim that the images were used as part of research into the capabilities of Webflow. Again, there Firaxis could simply counter that this was not done in conjuction with any research, and no research materials were published.