For me, I scrolled, clicked, but the page hijacked my screen, moved its position by force, and I was not certain which pane I was on immediately. It broke my sense of continuity.

I am only being literal when I say this, but as someone who is actively keeping an eye out for this sort of thing (CSS frameworks, UI kits), I lost interest pretty immediately when I saw that and closed the tab immediately. Assuming the people who made this page also made the UI kit, it tells me their web design values run contrary to mine.

I don't even fall into one of the exceptional cases, and this was a very bad using-a-website experience for me.