at-rule-descriptor-no-unknown

Disallow unknown descriptors for at-rules.

@counter-style foo {
  unknown-descriptor: cyclic;
/**                ↑
 * Descriptors like this */
}

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

You can filter the CSSTree Syntax Reference to find out what descriptors are known for an at-rule.

The message secondary option can accept the arguments of this rule.

This rule checks descriptors within at-rules. To check properties, you can use the property-no-unknown rule.

Prior art:

Options

The following patterns are considered problems:

@counter-style foo {
  unknown-descriptor: cyclic;
}

@property --foo {
  unknown-descriptor: "<color>";
}

The following patterns are not considered problems:

@counter-style foo {
  system: cyclic;
}

@property --foo {
  syntax: "<color>";
}