{ lib, inputs, config, pkgs, hostname, gpu, ... }: {
  imports = [ inputs.kde2nix.nixosModules.plasma6 ];

  # Enable sound with pipewire.
  sound.enable = true;
  hardware.pulseaudio.enable = false;
  security.rtkit.enable = true;
  services.pipewire = {
    enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    pulse.enable = true;
  };

  # Configure keymap in X11
  services.xserver = {
    enable = true;
    layout = "us";
    xkbVariant = "";
    autorun = true;
    videoDrivers = [ ] ++ lib.optional (builtins.isString gpu) gpu;
  };

  services.xserver = {
    # https://nixos.org/manual/nixos/stable/index.html#chap-gnome
    # Enable the KDE Plasma 6 Desktop Environment.
    desktopManager.plasma6.enable = true;
  };

  environment.systemPackages = with pkgs; [
    arc-kde-theme
    papirus-icon-theme
    plasma-theme-switcher
  ];
}