Webstorm showing errors on correct code

I have this code:

h2 {
    color: white;
    text-shadow: 0px 0px 15px black;
    @supports (-webkit-overflow-scrolling: touch) {
        text-shadow: none;
    }
}

That is showing as bad:

This code is valid less, producing:

h2 {
color: white;
text-shadow: 0px 0px 15px black;
}
@supports (-webkit-overflow-scrolling: touch) {
h2 {
text-shadow: none;
}
}

And can be validated here:

https://jigsaw.w3.org/css-validator/validator