Hi, I would like to contribute to this issue! 🙇

Still working on this one, will do a status update as soon as I can 🙇

• Wrote a visitor to return the Selector groupings in a sheet.

Since we need to compare the all the selectors in the sheet against each other, as well as being able to compare whether selectors are equivalent I need to do some things to "resolve" the selector.

I created a draft PR (#2660)

Working on trying to get the selector resolver to properly resolve the & case, and then to work with AtRule.
I think the implementation is going to end up much larger than I anticipated, mainly to resolve selectors so they can be compared for equivalents.

I want to eventually remove the Visitor but right now it's the easiest way to get the nodes of interest, my other option is to get the entire list and handle it (seems like a lot of traversing for the run).

If there is some way to persist State between multiple runs that I can use to track the resolved selectors then it may be easier to compare by just fetching the upper level CSS rules. 🤔

Update: working on another solution that does not rely on recursion (see the PR for context). Will attempt to reduce the scope covered by it so it's easier to review.