Typescript 3.3 introduces a breaking change:[No self or forward references in type parameter defaults](https://github.com/Microsoft/TypeScript/pull/29179) This makes the definition of `Value` in `packages\alfa-css\src\values.ts` invalid.
Typescript 3.3 introduces a breaking change:No self or forward references in type parameter defaults
This makes the definition of
Valueinpackages\alfa-css\src\values.tsinvalid.