at-rule-descriptor-value-no-unknown

Disallow unknown values for descriptors within at-rules.

@counter-style foo {
  system: unknown;
/**       ↑
 * Values like this */
}

This rule considers descriptors and values 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 values are known for a descriptor of an at-rule, and use the languageOptions configuration property to extend it.

This rule checks descriptor values within at-rules. You can use declaration-property-value-no-unknown to disallow unknown values for properties within declarations, and at-rule-descriptor-no-unknown to disallow unknown descriptors for at-rules.

warning

This rule is only appropriate for CSS. You should not turn it on for CSS-like languages, such as SCSS or Less.

note

When using this rule, we recommend turning off these overlapping rules or configuring them to ignore the overlaps:

• color-no-invalid-hex
• function-linear-gradient-no-nonstandard-direction
• function-no-unknown
• string-no-newline
• unit-no-unknown

Prior art:

• stylelint-csstree-validator

Options

true

{
  "at-rule-descriptor-value-no-unknown": true
}

The following patterns are considered problems:

@counter-style foo {
  system: unknown;
}

@property --foo {
  syntax: unknown;
}

The following patterns are not considered problems:

@counter-style foo {
  system: numeric;
}

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