[css-align][css-grid] Baseline shared alignment context for items spanning more than one row/column #1037
Description
The spec states the following to define when boxes may share an alignment context:
https://drafts.csswg.org/css-align-3/#baseline-terms
Boxes share an alignment context along a particular axis when they are:
- grid items in the same row, along the grid’s row (inline) axis, established by the grid container
- grid items in the same column, along the grid’s colum (block) axis, established by the grid container
I had initially understood that items spanning several tracks (eg, grid-row: 1 / 3) would still share an alignment context with items placed at a single track (eg, grid-row: 1 / 2), since they indeed share the first row.
My understanding also suggested that such item spanning several tracks didn't share an alignment context with items located at second row (eg, grid-row: 2 / 3), since I was considering only the first track for items spanning multiple tracks.
First of all, are my assumptions correct ? Either they are or not I think we should have something in the spec to address this issue and explain how we should treat spanning grid items.
If my assumptions are correct, then I have some implementation issues because the scenario described above may result on a baseline offset which could cause that the items located at a single track to be placed outside their grid area.