[csswg-drafts] [css-position] Static position of abspos top layer elements inside fixed pos. (#9939)

emilio has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-position] Static position of abspos top layer elements inside fixed pos. ==
This is the cyclic / ordering issue that I was concerned about in #8040.

Both Firefox and Blink get it wrong. WebKit gets it right, but I'm not sure what they're doing, maybe they're laying out the abspos twice?

```html
<!DOCTYPE html>
<meta charset="utf-8">
<style>
#outer {
  position: fixed;
  width: 200px;
  height: 200px;
  border: 2px solid blue;
}
dialog {
  display: inline;
  position: absolute;
  inset: auto;
}
</style>
Some content.
<br>
<br>
<br>
<br>
<br>
Some more.
<br>
<div id=outer>
  Fixed-pos.
  <dialog>Absolute popover inside fixed element</dialog>
</div>
<script>
  document.querySelector("dialog").showModal();
</script>
```

The main issue here is that you have:

 * Viewport box
   * ICB
     * Abspos
   * Fixedpos

So you lay out the abspos _before_ the fixedpos, and the static position isn't computed yet.

cc @rlbuis @bfgeek @chrishtr 

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/9939 using your GitHub account


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Received on Tuesday, 13 February 2024 01:52:11 UTC