I would add some CSS limitations as well. All sticky headers scroll out of the way as soon as you scroll down. No obnoxious full screen stickies, especially those appearing after a timeout or detecting that my mouse goes up. Proper contrast, font size and line width. So basically extended reader mode.
To implement this, you would have to prevent JavaScript from reading how far down you’ve scrolled or which element your mouse is hovering over, or else JavaScript could repeatedly insert absolutely-positioned elements over the part of the page you’re looking at.
