theme: simplify css with stylix

homeManagerModules/theme.nix

@@ -5,9 +5,41 @@
   ...
 }: let
   cfg = config.ar.home.theme;
+in {
+  config = lib.mkIf cfg.enable {
+    home.packages = [
+      pkgs.gnome.adwaita-icon-theme
+      pkgs.liberation_ttf
+    ];
 
-  gtk = {
+    gtk.iconTheme = {
-    extraCss =
+      name =
+        if config.stylix.polarity == "dark"
+        then "Papirus-Dark"
+        else "Papirus";
+
+      package = pkgs.papirus-icon-theme.override {color = "adwaita";};
+    };
+
+    qt = {
+      enable = true;
+      platformTheme.name = "qtct";
+
+      style = {
+        name =
+          if config.stylix.polarity == "dark"
+          then "Adwaita-Dark"
+          else "Adwaita";
+
+        package = pkgs.adwaita-qt6;
+      };
+    };
+
+    stylix.targets.gtk.extraCss = ''
+      // Control rounded corners
+      window.background { border-radius: ${toString cfg.borderRadius}; }
+
+      ${
         lib.strings.optionalString
         cfg.gtk.hideTitleBar
         ''
@@ -30,44 +62,8 @@
           window.csd decoration { /* gtk3 */
             box-shadow: none;
           }
+        ''
+      }
     '';
   };
-in {
-  config = lib.mkIf cfg.enable {
-    home = {
-      packages = [
-        pkgs.adwaita-qt
-        pkgs.gnome.adwaita-icon-theme
-        pkgs.liberation_ttf
-      ];
-    };
-
-    gtk = {
-      iconTheme = {
-        name =
-          if config.stylix.polarity == "dark"
-          then "Papirus-Dark"
-          else "Papirus";
-
-        package = pkgs.papirus-icon-theme.override {color = "adwaita";};
-      };
-
-      gtk3 = {inherit (gtk) extraCss;};
-      gtk4 = {inherit (gtk) extraCss;};
-    };
-
-    qt = {
-      enable = true;
-      platformTheme.name = "qtct";
-
-      style = {
-        name =
-          if config.stylix.polarity == "dark"
-          then "Adwaita-Dark"
-          else "Adwaita";
-
-        package = pkgs.adwaita-qt6;
-      };
-    };
-  };
 }