This release features the following (compared to 2.0):
- NSAC 2.1.
- Support for empty custom properties ("--foo:;").
- env() is now processed in computed values.
- The parsing is a bit more Windows-friendly. Previous versions produced
different whitespaces when parsing custom CSS rules for Windows and Unix.
That was enough to break some unit tests on Windows.
In short, 2.1.0 is a bit more spec-compliant and a good refinement over 2.0.