Many good points in there. One that I run into on a regular base and that can't be fixed right now: > Selectors have terrible future-proofing. We should have s

Many good points in there. One that I run into on a regular base and that can't be fixed right now: > Selectors have terrible future-proofing. We should have split on top-level commas, and only ignored unknown/invalid segments, not the entire thing. That forces you to duplicate declarations for backward-compatibility. For example, you can't combine those two selectors: /* works */ :user-invalid {} :-moz-ui-invalid {} /* breaks */ :user-invalid, :-moz-ui-invalid {} Somewhat related to the link: https://github.com/jensimmons/cssremedy https://github.com/jensimmons/cssremedy tries to "fix" some of those issues.