pinwheel: Tint work Firefox toolbars instead of outlining the window

hosts/pinwheel/modules/firefox/default.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ pkgs, config, ... }:
 let
   wrapped = pkgs.wrapFirefox pkgs.firefox-devedition-unwrapped {
     extraPolicies = {
@@ -100,8 +100,12 @@ in
           };
 
           userChrome = ''
-            #main-window {
+            #navigator-toolbox,
-              border: 2px solid #9400FF !important;
+            #nav-bar {
+              background-image: linear-gradient(
+                color-mix(in srgb, #${config.lib.colors.foreground} 5%, transparent),
+                color-mix(in srgb, #${config.lib.colors.foreground} 5%, transparent)
+              ) !important;
             }
           '';
         };