CSS/SCSS Unknown function 'light-dark'

A question about handling this type of error in general, but here with a specific example pertaining to the relatively new CSS light-dark() function.

@supports (color: light-dark(black, white)) {
    color: light-dark(
       color-mix(in srgb, var(--color-bortle) 50%, black),
       color-mix(in srgb, var(--color-bortle) 50%, white)
    );
    background: color-mix(in srgb, var(--color-bortle) 10%, transparent);
}

PHPStorm flags ‘light-dark’ with Unknown function ‘light-dark’, which looks like it is tied to CssInvalidFunction under inspections. And to the CSS plugin? But after some searching, I have found no way to add it as a custom function, nor to add some sort of inline comment to ignore CssInvalidFunction for this case. Only a way to adjust error handling for that inspection on a global scale, which is not ideal when a truly non-existent function would be a problem.

Any advice on how to handle a case like this in the IDE?

Thanks in advance!