at-rule-no-unknown

Disallow unknown at-rules.

    @unknown (max-width: 960px) {}
/** ↑
 * At-rules like this */

This rule considers at-rules defined in the CSS Specifications, up to and including Editor's Drafts, to be known.

Options

The following patterns are considered problems:

@unknown {}

The following patterns are not considered problems:

@charset "UTF-8";

@CHARSET "UTF-8";

@media (max-width: 960px) {}

@font-feature-values Font One {
  @styleset {}
}

Given:

["/^--my-/", "--custom"]

The following patterns are not considered problems:

@--my-at-rule "x.css";

@--my-other-at-rule {}

@--custom {}