I wish the browser could present a huge screen (2000px high or bigger) to the webpage and render it. After that I would love to scroll this viewport without th

I wish the browser could present a huge screen (2000px high or bigger) to the webpage and render it. After that I would love to scroll this viewport without the page even knowing about it. This would resolve all problems with position fixed and also block the page from showing real modals once scrolling starts.