Use specialisation to switch themes on NixOS

os/geoffrey.nix

@@ -1,4 +1,4 @@
-{ pkgs, config, ... }:
+{ pkgs, lib, config, ... }:
 {
   imports = [
     <home-manager/nixos>
@@ -32,6 +32,12 @@
     useGlobalPkgs = true;
   };
 
+  specialisation = {
+    dark.configuration.frogeye.polarity = "dark";
+    light.configuration.frogeye.polarity = "light";
+  };
+
+
   # Because everything is encrypted and I'm the only user, this is fine.
   services.xserver.displayManager.autoLogin.user = "geoffrey";
 }