Add thunderbird module

modules/default.nix

@@ -5,6 +5,7 @@
     ./desktop/mimeapps.nix
     ./desktop/apps/qbittorrent.nix
     ./desktop/apps/slack.nix
+    ./desktop/apps/thunderbird.nix
     ./desktop/apps/zoom.nix
     ./desktop/browsers/firefox.nix
     ./desktop/gaming/emulators.nix

modules/desktop/apps/thunderbird.nix

@@ -0,0 +1,32 @@
+{ config, lib, pkgs, inputs, ... }:
+
+with lib;
+with lib.my;
+let cfg = config.modules.desktop.apps.thunderbird;
+in {
+  options.modules.desktop.apps.thunderbird = {
+    enable = mkBoolOpt false;
+  };
+  
+  config = mkIf cfg.enable {
+    home.file.".mozilla/thunderbird/Default/chrome/thunderbird-gnome-theme".source = inputs.thunderbird-gnome-theme;
+
+    home.programs.thunderbird = {
+      enable = true;
+      profiles.Default = {
+        isDefault = true;
+        userChrome = ''
+          @import "thunderbird-gnome-theme/userChrome.css";
+        '';
+        userContent = ''
+          @import "thunderbird-gnome-theme/userContent.css";
+        '';
+        settings = {
+          ## GNOME theme
+          "toolkit.legacyUserProfileCustomizations.stylesheets" = true;
+          "svg.context-properties.content.enabled" = true;
+        };
+      };
+    };
+  };
+}