stylecow plugin custom-selector

Stylecow plugin to work with the @custom-selector at-rule, available in CSS Media Queries Level 4.

You write:

@custom-selector --heading h1, h2, h3, h4, h5, h6;
@custom-selector --main-world strong.main;
 
body --heading --main-world {
    color: blue;
}

And stylecow converts to:

body :matches(h1, h2, h3, h4, h5, h6) strong.main {
    color: blue;
}

More demos in the tests folder