Anchor positioning doesn't work across containing blocks

### MDN URL

https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_anchor_positioning

### What specific section or headline is this issue about?

CSS Anchor Positioning

### What information was incorrect, unhelpful, or incomplete?

Currently any new stacking context created between the anchored element and its anchor element breaks the connection. This includes positioned elements, those with `will-change` or those with a transforms or filters applied. That's not captured in the docs and is frustratingly difficult to debug.

### What did you expect to see?

Information on avoiding creating new stacking contexts.

### Do you have any supporting links, references, or citations?

_No response_

### Do you have anything more you want to share?

The anchor API feels unfinished and has some serious limitations including the inability to properly control visibility, such as hiding an item that has no valid anchor in scope.

### MDN metadata

Page report details

* Folder: `en-us/web/css/css_anchor_positioning`
* MDN URL: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_anchor_positioning
* GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/web/css/css_anchor_positioning/index.md
* Last commit: https://github.com/mdn/content/commit/bc761c19c07b875eb889d4aad87b18d8443da339
* Document last modified: 2025-08-04T12:04:41.000Z