It looks like it is almost all keyboard interactions. The space bar is also broken, and the up/down arrow keys select the next/previous paragraph rather than scrolling the page up or down. Not only that, but the content is loaded by JavaScript, so disabling JS results in a blank page.

Can’t pinch to zoom on mobile either. Can we please just go back to basic HTML and image tags? Rendering everything in client side JavaScript is worse in every way.