Back with an update with news of CSS Grid Level 2. Level 2 is mostly about the subgrid feature which was removed from Level 1 pending more discussions about how it should work. Subgrid is currently being implemented in Firefox, and I’ve been testing some early builds in order to be able to document the specification.
I have added some subgrid examples to this site. As soon as the feature ships in a regular build of Nightly you can come try them for yourself! There are also some screenshots in this post on my blog.
For more detail about subgrid see my post on Smashing Magazine from last year detailing the features of the spec - CSS Grid Level 2: Here Comes Subgrid.