Holy shit, you're right. It's so bad on mobile. It's broken in so many ways. It scrolls horizontally and vertically. At one point I somehow scrolled the header instead of the body. I want to debug the page just so I avoid the same issues on my own sites.

Who the hell does scroll hijacking on mobile?

This sort of thing is the absolute pits. Now that position: sticky is in CSS, are there any good reasons browsers don't rate limit onscroll event handlers?