You need to
before you can comment on or make changes to this bug.
This is a master bug to track the implementation of CSSRegions spec in WebKit. We'll add various patches as dependency/blocker of this bug as they come in. The url contains the link to the CSSWG spec.
For reference, Adobe did a prototype implementation:
The implementation team will contribute it as incremental patches so that it can undergo the review process progressively and be adjusted/modified/improved as needed.