Braw mornin' TAG!

I'm requesting a TAG review of CSS Subgrid.

You can "nest" grids by making a grid item a grid container. These grids however are independent of the parent grid and of each other, meaning that they do not take their track sizing from the parent grid. This makes it difficult to line nested grid items up with the main grid. If you set the value subgrid on grid-template-columns, grid-template-rows or both, instead of creating a new track listing the nested grid uses the tracks defined on the parent.

• Explainer: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Grid_Layout/Subgrid
• Specification URL: https://drafts.csswg.org/css-grid-2
• Tests: https://wpt.fyi/results/css/css-grid/subgrid
• Security and Privacy self-review: https://github.com/w3c/csswg-drafts/issues/7003
• GitHub repo: https://github.com/w3c/csswg-drafts/issues
• Primary contacts:
  • Ethan Jimenez (@ethanjv), Microsoft
  • Daniel Libby (@dlibby-), Microsoft
• Organization(s)/project(s) driving the specification: Microsoft, Google, Firefox, Apple
• Key pieces of existing multi-stakeholder review or discussion of this specification: None
• External status/issue trackers for this specification:
  • https://chromestatus.com/feature/5663795354533888

Further details:

• I have reviewed the TAG's Web Platform Design Principles
• Relevant time constraints or deadlines: None
• The group where the work on this specification is currently being done: CSSWG
• The group where standardization of this work is intended to be done (if current group is a community group or other incubation venue): CSSWG
• Major unresolved issues with or opposition to this specification: None
• This work is being funded by: Microsoft, Google, Firefox, Apple

We'd prefer the TAG provide feedback as (please delete all but the desired option): 🐛 open issues in our GitHub repo for each point of feedback