The blog link in my original post shows images of the themes. They aren't obnoxious. I tried them. It's similar to their usual formats that have been renamed to make it more fun. They've also renamed "night mode" to be "night owl". Turning privacy mode on is "invisibility cloak".
The Oyster Review is featuring the Harry Potter series this week. For example, there is currently posted an essay by author Lauren Oliver about JKR's influence on her life.
https://review.oysterbooks.com