Support for :nth-child(An+B) where A is negative

[kpldvnpne]

I have a need to select the first two children. According to this MDN doc, I should be able to do something like this with CSS selectors:

:nth-child(-n+2)

I tried this selector with pup, but it behaves like there is no - in front of n. That is, it behaved the same as :nth-child(n+2).

Is this syntax not supported?