First Public Working Draft: CSS Anchor Positioning

The CSS Working Group has published a First Public Working Draft of CSS Anchor Positioning. This allows a positioned element (such as a tooltip or pop-up footnote) to size and position itself relative to one or more "anchor elements" elsewhere on the page. Because the anchoring element could have any size or position on the page, a flexible fallback scheme is also defined whereby a series of rules is tried until one is found that does not result in the positioned element overflowing its containing block.