{ lib, inputs, config, pkgs, username, 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
    arc-theme
    papirus-icon-theme
    plasma-theme-switcher
    tailscale-systray
  ];

  systemd.user.services = {
    "get-theme-times" = {
      enable = true;
      path = [ pkgs.curl ];
      script = "curl wttr.in?format=j1 > /tmp/wttr.in";
      after = [ "networking-online.target" ];
      serviceConfig.Type = "oneshot";
      onSuccess = [
        "light-theme.service"
        "dark-theme.service"
      ];
    };
    light-theme = {
      enable = true;
      path = [ pkgs.at pkgs.fx pkgs.nodejs ];
      script = ''
        whoami
        id
        source ~/.bashrc
        echo "/run/current-system/sw/bin/plasma-apply-colorscheme -platform offscreen Arc" | sudo ${pkgs.at}/bin/at `${pkgs.fx}/bin/fx /tmp/wttr.in .weather[0].astronomy[0].sunrise`
      '';
      serviceConfig.Type = "oneshot";
    };
    dark-theme = {
      enable = true;
      path = [ pkgs.at pkgs.fx pkgs.nodejs ];
      script = ''
        whoami
        id
        source ~/.bashrc
        echo "/run/current-system/sw/bin/plasma-apply-colorscheme -platform offscreen ArcDark" | sudo ${pkgs.at}/bin/at `${pkgs.fx}/bin/fx /tmp/wttr.in .weather[0].astronomy[0].sunset`
      '';
      serviceConfig.Type = "oneshot";
    };
  };

  systemd.user.timers = {
    "light-theme" = {
      enable = false;
      partOf = [ "light-theme.service" ];
      timerConfig.OnCalendar = [ "*-*-* *:*:00" ];
    };
    "dark-theme" = {
      enable = false;
      partOf = [ "dark-theme.service" ];
      timerConfig.OnCalendar = [ "*-*-* *:*:00" ];
    };
  };
}