Display the button only when the user is scrolling the page
Summary
The scroll to top button is visible at the bottom of the screen for any page, any modern content page (analytics, site content, list/library, etc.) any time.
Current behavior
The button is visible even if the user does not scroll the page.
Expected behavior
Hide the button as long as the user does not scroll the page. Once at the top of the page again, hide the button again.