[css-position-3] Containing block of dialog fixed position children #8040
Description
I wonder what the cb should be of the fixed positioned dialog child:
<html>
....
<div style="transform:...">
<dialog> <!-- in top layer -->
<div style="position:fixed">
....
If this test is valid then the fixed positioned dialog child'cb is html aka viewport:
https://wpt.fyi/results/html/semantics/interactive-elements/the-dialog-element/top-layer-stacking.html?label=experimental&label=master&aligned
I have heard some opinions though that the dialog itself should be the cb.
I can't really conclude from the spec what the cb should be, for one thing what should qualify something to be a fixed positioning containing block seems not specified in one location/spec. Is there something I am missing in the spec and/or what do people think should be the cb in the example?