Follow system theme

Please follow the system theme:

![image](https://github.com/libretro/ludo/assets/23485114/74fc5035-d7ad-4254-a198-c5f1c91106c7)

![image](https://github.com/libretro/ludo/assets/23485114/bf957ebe-3ede-4ced-a6d6-5ba983a7a72a)
