{
  pkgs,
  config,
  ...
}:

let
  # WARNING: Official theme, but archived since Jun 2024.
  themePackage = pkgs.catppuccin-gtk.override {
    accents = [ "blue" ];
    size = "standard";
    variant = "mocha";
  };
  themeName = "catppuccin-mocha-blue-standard";

  iconPackage = pkgs.kdePackages.breeze-icons;
  iconName = "breeze-dark";
in
{
  home-manager.users.kalle.gtk = {
    enable = true;
    theme = {
      package = themePackage;
      name = themeName;
    };
    iconTheme = {
      package = iconPackage;
      name = iconName;
    };
    # cursorTheme = {package name size}; defaults to home.pointerCursor vals.

    gtk3 = {
      extraConfig.gtk-application-prefer-dark-theme = true;
    };
    gtk4 = {
      extraConfig.gtk-application-prefer-dark-theme = true;
    };
  };

  # Some software will only behave with theming if you set this (i.e. adjust
  # font color), especially software that has heavy integration with DEs
  # normally and GTK4 stuff. Also for Wayland software this may work only if
  # the gtk desktop portal is installed.
  home-manager.users.kalle.dconf.settings = {
    "org/gnome/desktop/interface" = {
      color-scheme = "prefer-dark";
      gtk-theme = themeName;
      icon-theme = iconName;
    };
  };
}