sway/swaynag: Deduplicate config

users/simon/modules/sway.nix

@@ -270,23 +270,26 @@ lib.mkIf nixosConfig.sbruder.gui.enable {
     wdisplays # graphical output manager
   ];
 
-  # FIXME deduplicate (everything except text is redundant)
-  xdg.configFile."swaynag/config".text = ''
+  xdg.configFile."swaynag/config".text =
+    let
+      # adding it to the header doesn’t work since the defaults overwrite it
+      commonConfig = ''
+        background=fdf6e3
+        border-bottom=eee8d5
+        border=eee8d5
+        button-background=eee8d5
+      '';
+    in
+    ''
       font=Monospace 12
 
       [warning]
       text=b58900
-    background=fdf6e3
-    border=eee8d5
-    border-bottom=eee8d5
-    button-background=eee8d5
+      ${commonConfig}
 
       [error]
       text=dc322f
-    background=fdf6e3
-    border=eee8d5
-    border-bottom=eee8d5
-    button-background=eee8d5
+      ${commonConfig}
     '';
 
   # home-manager’s waybar module performs additional checks that are overly strict