I am batman

modules/lightdm/aqua-theme.nix

@@ -0,0 +1,45 @@
+{ pkgs, lib, config, ... }:
+
+let
+  aqua-theme = pkgs.stdenv.mkDerivation {
+    pname = "aqua-lightdm-webkit-theme";
+    version = "1.0";
+
+    src = pkgs.fetchzip {
+      url = "https://github.com/paysonwallach/aqua-lightdm-webkit-theme/archive/master.zip";
+      sha256 = "sha256-+nn2JN+l/SF6fNH/caT/JIptHilRdwLZ7FlFMD68VxA=";
+      stripRoot = true;
+    };
+
+    installPhase = ''
+      mkdir -p $out/share/lightdm-webkit/themes/aqua
+      cp -r . $out/share/lightdm-webkit/themes/aqua/
+    '';
+
+    meta = with pkgs.lib; {
+      description = "macOS-inspired LightDM Webkit greeter theme";
+      homepage = "https://github.com/paysonwallach/aqua-lightdm-webkit-theme";
+      platforms = platforms.linux;
+    };
+  };
+in
+{
+  config = lib.mkIf config.services.xserver.displayManager.lightdm.enable {
+    # Install the aqua theme (for future webkit greeter use)
+    environment.systemPackages = [
+      aqua-theme
+    ];
+
+    # Create symlink for theme to be accessible to lightdm
+    system.activationScripts.aqua-lightdm-theme = {
+      text = ''
+        mkdir -p /usr/share/lightdm-webkit/themes
+        if [ -L /usr/share/lightdm-webkit/themes/aqua ]; then
+          rm /usr/share/lightdm-webkit/themes/aqua
+        fi
+        ln -sf ${aqua-theme}/share/lightdm-webkit/themes/aqua /usr/share/lightdm-webkit/themes/aqua
+      '';
+      deps = [];
+    };
+  };
+}

modules/lightdm/default.nix

@@ -0,0 +1,6 @@
+{ ... }:
+{
+  imports = [
+    ./aqua-theme.nix
+  ];
+}