[csswg-drafts] [css-grid-3][masonry] Clarify that optimized track sizing is expected in grid containers with subgridded masonry (#11347)

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

== [css-grid-3][masonry] Clarify that optimized track sizing is expected in grid containers with subgridded masonry ==
Link to the spec: [Optimized Track Sizing](https://drafts.csswg.org/css-grid-3/#track-sizing-performance)

Currently, the combined spec for masonry containers [introduced a section](https://drafts.csswg.org/css-grid-3/#track-sizing) to remove the cyclic dependency between placement and track sizing in masonry, which makes the track sizing algorithm consider auto-placed items to be considered in all intrinsic tracks.

The track sizing algorithm is presumably only applicable to masonry containers. However, when a submasonry is subgridded to a regular grid container, the [Subgrid Item Contributions](https://drafts.csswg.org/css-grid-3/#track-sizing-subgrid) section states that the notion of placing every auto-placed item in all possible intrinsic tracks spanned by the submasonry is also expected for the parent grid container.

This makes sense, but there's an implication that would be good to clarify in the spec: The concept of the [virtual masonry item is introduced](https://drafts.csswg.org/css-grid-3/#track-sizing-performance) to avoid poor performance due to all auto-placed items being able to contribute to all intrinsic tracks, but the virtual masonry item concept could also be applicable to grid containers that have a submasonry within.

Either the virtual masonry items are the ones to be subgridded to a parent grid, or the track sizing algorithm for grid containers should also apply this optimization. It would be good to clarify that this is expected behavior, since they both have subtle implications to how grid/masonry containers collect and place subgridded items, and to the resulting tracks of a regular grid with nested masonry.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/11347 using your GitHub account


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Received on Tuesday, 10 December 2024 18:43:57 UTC