Buttons are now fixed to the bottom of the window on posts instead of being under the article. This means they are always visible.
You no longer have to scroll to the bottom of posts to bookmark or otherwise react to a post. There is also a "jump to discussion" button and a tweet button. All things folks have asked for a lot.
This was inspired by this post, where @entrptaher proposes the change:
Even though the post is from June, we thought hard about whether this was the right idea. Ultimately we felt it would improve the overall usability of the site, and leaves us open to some nice future additions.
If you're not a fan of this adjustment, you may consider reverting it via a user script.
Anyway, we will pay attention to how the UI adjustment plays out and determine whether additional changes are needed.