stylecow plugin custom-media

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

You write:

@custom-media --small-viewport (max-width: 30em);
 
@media (--small-viewport) {
	body {
		color: blue;
	}
}

And stylecow converts to:

@media (max-width: 30em) {
	body {
		color: blue;
	}
}

More demos in the tests folder