Media Use Custom Media is a stylelint rule to enforce usage of custom media queries in CSS.

Add stylelint and Media Use Custom Media to your project.

npm install stylelint stylelint-media-use-custom-media --save-dev

Add Media Use Custom Media to your stylelint configuration.

{
  "plugins": [
    "stylelint-media-use-custom-media"
  ],
  "rules": {
    "csstools/media-use-custom-media": "always" || "always-known" || "known" || "never" || "ignore"
  }
}

If the first option is "always" or true, then Media Use Custom Media requires all @media queries to use Custom Media, and the following patterns are not considered violations:

@media (--sm) {}

@media (--sm), (--md) {}

@media screen and (--sm) {}

While the following patterns are considered violations:

@media (max-width: 40rem) {}

@media (max-width: 40rem), (--md) {}

If the first option is "never" or false, then Media Use Custom Media requires all @media queries to not use Custom Media, and the following patterns are not considered violations:

@media (max-width: 40rem) {}

@media screen and (max-width: 40rem) {}

While the following patterns are considered violations:

@media (--md) {}

@media screen and (--md) {}

@media (--md), (max-width: 40rem) {}

If the first option is "known", then Media Use Custom Media requires all @media queries referencing Custom Media to be known from either @custom-media declarations in the file or imported using the second option. Then the following patterns are not considered violations:

@custom-media --sm (min-width: 40rem);

@media (--sm) {}

@media (--sm), (min-width: 40rem) {}

While the following patterns are considered violations:

@media (--md) {}

@media (--md), (min-width: 40rem) {}

If the first option is "known", then Media Use Custom Media requires all @media queries to use known Custom Media from either @custom-media declarations in the file or imported using the second option. Then the following patterns are not considered violations:

@custom-media --sm (min-width: 40rem);

@media (--sm) {}

While the following patterns are considered violations:

@custom-media --sm (min-width: 40rem);

@media (--sm), (min-width: 40rem) {}

@media (--md) {}

If the first option is "ignore" or null, then Media Use Custom Media does nothing.

When the first option is "always-known" or "known", then the second option can specify sources where Custom Properties should be imported from by using an importFrom key. These imports might be CSS, JS, and JSON files, functions, and directly passed objects.

// .stylelintrc
{
  "plugins": [
    "stylelint-media-use-custom-media"
  ],
  "rules": {
    "csstools/media-use-custom-media": ["known", {
      "importFrom": [
        "path/to/file.css", // => @custom-media --sm (min-width: 40rem);
        "path/to/file.json" // => { "custom-media": { "--sm": "(min-width: 40rem)" } }
      ]
    }
  }
}