Add structure for Selectors
Add Attribute and simple selectors

…not sure these are the best way to show right now
Add combinator selectors
Add pseudo classes
Add pseudo elements
Add attribute selectors 4
Add pseudo classes 4
Add combinators 4
Add CSS UI 3 pseudo classes

…and one from Selectors 4 (placeholder-shown) that claims to be from
Basic UI but isn’t in the draft.
Add CSS UI 3 pseudo elements
Add CSS GCPM and CSS Lists 3 pseudo elements
Add page pseudo classes, and non element selectors
Add Shadow DOM pseudo classes
Add Shadow DOM combinators
Add Fullscreen pseudos
flex missing bracket and missing [ ] around specs