diff --git a/modules/gtk/hm.nix b/modules/gtk/hm.nix
index 71729d10..44776b2b 100644
--- a/modules/gtk/hm.nix
+++ b/modules/gtk/hm.nix
@@ -1,16 +1,40 @@
 { pkgs, config, lib, ... }:
 
+with lib;
+
 let
-  css = config.lib.stylix.colors {
+  cfg = config.stylix.targets.gtk;
+
+  baseCss = config.lib.stylix.colors {
     template = builtins.readFile ./gtk.mustache;
     extension = "css";
   };
- 
-in {
-  options.stylix.targets.gtk.enable =
-    config.lib.stylix.mkEnableTarget "all GTK3, GTK4 and Libadwaita apps" true;
 
-  config = lib.mkIf config.stylix.targets.gtk.enable {
+  finalCss = pkgs.runCommandLocal "gtk.css" {} ''
+    echo ${escapeShellArg cfg.extraCss} >>$out
+    cat ${baseCss} >>$out
+  '';
+
+in {
+  options.stylix.targets.gtk = {
+    enable = config.lib.stylix.mkEnableTarget
+      "all GTK3, GTK4 and Libadwaita apps" true;
+
+    extraCss = mkOption {
+      description = ''
+        Extra code added to <literal>gtk-3.0/gtk.css</literal>
+        and <literal>gtk-4.0/gtk.css</literal>.
+      '';
+      type = types.lines;
+      default = "";
+      example = ''
+        // Remove rounded corners
+        window.background { border-radius: 0; }
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
     # programs.dconf.enable = true; required in system config
     gtk = {
       enable = true;
@@ -22,8 +46,8 @@ in {
     };
 
     xdg.configFile = {
-      "gtk-3.0/gtk.css".source = css;
-      "gtk-4.0/gtk.css".source = css;
+      "gtk-3.0/gtk.css".source = finalCss;
+      "gtk-4.0/gtk.css".source = finalCss;
     };
   };
 }