The sooner the better! I am anxiously awaiting subgrid as well, for all the reasons Shaun and Eric outlined. I add a lot of divs to my markup and repeat CSS that are there to get around the limitations of only being able to style direct descendants.

It would be so great to have this in Nightly asap. In some designs I want to implement I feel like the nested grid tracks should absolutely have a relationship to the parent grid, and when they don't, I just opt for a 'simpler' design.

Cards with different length content are a perfect use case for me. CSS Grid came to the rescue when I was working on complex cards, and subgrid would really finish the job.

This would be a huge advance is CSS layout capability. We use grid regularly on both client and internal projects - and always have to go out of our way trying to work around this missing feature. The issues above are not edge-cases, but problems that arise with most practical grid uses. Can't wait to have it land in nightly!

Subgrid is needed to ensure people markup isn't flattened which would cause accessibility issues in addition being an extremely useful tool for elements inside their parent grid containers. I'd love if it were implemented in Nightly!

A very common use-case is for a layout with grid items themselves having children that need to be laid out in a grid, while maintaining the same relationship with their grandparent grid, just like previous comments have described. Would be great for it to land ASAP so we can test out our ideas with it.

I agree with the previous comments. It would be great to define a grid further up the tree. Using display:contents or repeating the grid on every parent are not great workarounds. Giving access to a grandparent grid seems close to required for this to be usable beyond the most simple use cases.