The CSS scroll anchoring module defines a mechanism to prevent page movement due to DOM changes above the visible region of a scrolling box while the user is consuming the visible content.
Scroll anchoring attempts to keep the user's view of the document stable across layout changes. It works by selecting a DOM node (the anchor node) whose movement is used to determine adjustments to the scroll position. The anchor node is always a descendant of the scrolling box.
For scroll containers that are snapped to an element, scroll anchoring is limited to adjustments that would be allowed by re-snapping.
What is scroll anchoring, suppression triggers, and when and how to enable and disable this browser feature.