So siehts ganz gut aus !

node_modules/clean-css/lib/optimizer/level-2/properties/overrides-non-component-shorthand.js

@@ -0,0 +1,9 @@
+var compactable = require('../compactable');
+
+function overridesNonComponentShorthand(property1, property2) {
+  return property1.name in compactable &&
+    'overridesShorthands' in compactable[property1.name] &&
+    compactable[property1.name].overridesShorthands.indexOf(property2.name) > -1;
+}
+
+module.exports = overridesNonComponentShorthand;