Ignore "selector-type-no-unknown" rule.

.stylelintrc

@@ -1,6 +1,7 @@
 {
   "extends": "stylelint-config-standard",
   "rules": {
-    "no-descending-specificity": null
+    "no-descending-specificity": null,
+    "selector-type-no-unknown": null
   }
 }