What happens when you set root: null in Intersection Observer options?
When root is set to null in Intersection Observer options, the viewport (visible area of the browser window) becomes the root element. This is particularly useful for: 1) Detecting when elements enter or leave the user's view, 2) Implementing lazy loading for images or content as the user scrolls, 3) Tracking visibility for analytics purposes, 4) Creating infinite scroll implementations. This is the most common configuration as it allows you to track elements relative to what the user can actually see on their screen.