Scroll the viewer to the top of a page. The wrapper is in the DOM for every page from the moment the
document loads (only the canvas and overlay are windowed), so this works for a page whose boxes are
not mounted yet; the IntersectionObserver then mounts it. False when the page is not in the scroller.
Scroll the viewer to the top of a page. The wrapper is in the DOM for every page from the moment the document loads (only the canvas and overlay are windowed), so this works for a page whose boxes are not mounted yet; the IntersectionObserver then mounts it. False when the page is not in the scroller.