On browser windows of certain widths, when you scroll down to the bottom of the page under the post stream, the horizontal scroll bar appears. I believe this is a regression.
The best thing is, when you’re on the threshold of the bar appearing, the scroll bar ‘humps’ the bottom of the screen.
Here’s a video of exactly what I mean, on meta.discourse.org. Though I identified it first on our own discourse instance.
YouTube
This is happening with Chrome on Ubuntu, with a window width of approximately 960 (i.e. half of 1920), I can identify a couple of (separate) width ranges where it happens: around 935-975 pixels, and 855-880 pixels. There are also ranges where the scrollbar appears but without the amusing oscillation.