:nth-child(2n) selector results in parse error

[eritbh]

Possibly related to #342?

:nth-child(2n) {
  color: red;
}

As a workaround, this code validates:

:nth-child(2n+0) {
  color: red;
}

[ylafon]

Most probably related to #342 yes which start when real validation of aN+b was added.
Thanks for the report