Bug: Error thrown on `::-webkit-scrollbar-thumb:vertical`

[terebentina]

Parcel-css (the version included in parcel 2.4.0) throws when using ::-webkit-scrollbar-thumb:vertical (or :horizontal) although it passes with either ::-webkit-scrollbar-thumb or .class::-webkit-scrollbar-thumb or even the invalid .class:vertical.
You can see this in the parcel-css demo app (https://parcel-css.vercel.app) by using the following css:

::-webkit-scrollbar-thumb {
}

.a::-webkit-scrollbar-thumb {
}

.a:vertical {
}

::-webkit-scrollbar-thumb:vertical {
}

As soon as you remove the last class it compiles.

[kuangjm825]

I'm also getting the same error and the CSS I'm compiling has ::-webkit-scrollbar:horizontal

[devongovett]

According to the CSS spec, pseudo elements may only be followed by a user action pseudo class (e.g. :hover/:active). I guess webkit didn't follow this with their non-standard pseudo elements. 😞 https://www.w3.org/TR/selectors-4/#pseudo-element-states