Add treestyletab.css

users/jalr/modules/firefox/default.nix

@@ -380,4 +380,6 @@
     enable = true;
     browsers = [ "firefox" ];
   };
+
+  xdg.configFile."treestyletab.css".source = ./treestyletab.css;
 }

users/jalr/modules/firefox/treestyletab.css

@@ -0,0 +1,17 @@
+@media (prefers-color-scheme: light) {
+  tab-item:not(.active):not(.bundled-active):not(.highlighted),
+  #background {
+    --toolbar-non-lwt-bgcolor: ThreeDShadow;
+    --toolbar-non-lwt-textcolor: ButtonText;
+  }
+}
+
+@media (prefers-color-scheme: dark) {
+  #tabbar {
+    background-color: var(--in-content-page-background);
+  }
+}
+
+tab-item.coloredTabsHue0 tab-item-substance {
+  background: transparent;
+}