message: Hack to ignore
  as per bug in comment
diff: @@ -15,6 +15,9 @@ module.exports = {
  "number-leading-zero": null,
  "selector-list-comma-newline-after": null,
  "at-rule-no-unknown": null,
  - "scss/at-rule-no-unknown": true,
  + "scss/at-rule-no-unknown": [true, {
  + // https://github.com/vector-im/riot-web/issues/10544
  + "ignoreAtRules": ["define-mixin"],
  + }],
  }
  }
  