HM: add section detailing how to fix problems with themes not working (#371)

Co-authored-by: Mihai Fufezan <mihai@fufexan.net>

pages/Nix/Hyprland on Home Manager.md

@@ -126,3 +126,43 @@ wayland.windowManager.hyprland.plugins = [
 
 For examples on how to build hyprland plugins using nix see the
 [official plugins](https://github.com/hyprwm/hyprland-plugins).
+
+## Fixing problems with themes
+
+If your themes for mouse cursor, icons or windows don't load correctly, try setting them with `home.pointerCursor` and `gtk.theme`, which enable a bunch of compatibility options that should make the themes load in all situations.
+
+Example configuration:
+```
+  home-manager = {
+    useGlobalPkgs = true;
+    useUserPackages = true;
+    users.username = {
+      home = {
+        stateVersion = "23.05";
+        pointerCursor = {
+          gtk.enable = true;
+          # x11.enable = true;
+          package = pkgs.bibata-cursors;
+          name = "Bibata-Modern-Amber";
+          size = 32;
+        };
+      };
+      gtk = {
+        enable = true;
+        theme = {
+          package = pkgs.flat-remix-gtk;
+          name = "Flat-Remix-GTK-Grey-Darkest";
+        };
+        iconTheme = {
+          package = pkgs.libsForQt5.breeze-icons;
+          name = "breeze-dark";
+        };
+        font = {
+          name = "Sans";
+          size = 11;
+        };
+      };
+    };
+  };
+   
+```

pages/Nix/Hyprland on NixOS.md

@@ -94,3 +94,7 @@ in {
 
 {{< /tab >}}
 {{< /tabs >}}
+
+## Fixing problems with themes
+
+If your themes for mouse cursor, icons or windows don't load correctly, see the relevant section in [Hyprland on Home Manager](./Hyprland-on-Home-Manager).