You know those times you get a horizontal scrollbar when accidentally placing an element off the right edge of the browser window? It might be a menu that slides in or the like. Sometimes we to overflow-x: hidden; on the body to fix that, but that can sometimes wreck stuff like position: sticky;.
Well, you know how if you place an element off the left edge of a browser window, it doesn’t do that? That’s “data loss” and just how things work around here. It actually has to do with the direction of the page. If you were in a RTL situation, it would be the left edge of the browser window causing the overflow situation and the right edge where it doesn’t.
Emerson Loustau leverages that idea to solve a problem here. I’d be way too nervous messing with direction like this because I just don’t know what the side effects would be. But, hey, at least it doesn’t break position: sticky;.