clobber gtk css files

Author: codebam

flake.lock

@@ -154,4 +154,9 @@
   gtk = {
     gtk2.force = true;
   };
+
+  xdg.configFile = {
+    "gtk-3.0/gtk.css".force = true;
+    "gtk-4.0/gtk.css".force = true;
+  };
 }