This is somewhat similar to #7123, except for position:absolute instead of position:relative.

If a subgrid is position:absolute should all top/left/right/bottom values be ignored, and we should just stretch and position across the corresponding grid area in the parent? Should we (similar to one option for relative) try to respect these as much as possible while still forcing the width/height to the stretched value (if both left and right are set, what's the precedence between each of these and the stretched width?)?

What happens if a position:absolute subgrid doesn't cover any grid tracks and only covers the padding area of the parent (grid-row: auto / 1)? Should this be listed as an explicit reason that the specified value of subgrid isn't applied?