Settings and themes

One set of fonts and one colour theme is applied across the terminal, editors, browser, shell prompt, compositor, desktop shell, GTK, and the boot loader. The values are defined once in flake.nix and reach every module as the settings argument.

Default settingsCopy Anchor Link

defaultSettings = {
  fonts = {
    sans = "0xPropo";
    mono = "0xProto";
    terminalSize = 11;
  };
  gaming.vrrOutput = null;
  theme = import ./lib/themes.nix { family = "meowsoot"; };
};

• fonts.sans and fonts.mono name the families used by fontconfig, GTK, Ghostty, Noctalia, and the editors. The fonts are installed through the portable desktop-base profile.
• fonts.terminalSize is the terminal font size.
• gaming.vrrOutput names the display that gets on-demand variable refresh in Niri; null disables it.
• theme is a whole theme family loaded from lib/themes.nix.

Per-host overridesCopy Anchor Link

defaultSettings is passed to every host through specialArgs (NixOS) or extraSpecialArgs (Home Manager). Each host then publishes its resolved settings through _module.args.settings. This lets a host layer overrides on top of the defaults before any module reads them:

# hosts/home/niflheim.nix
_module.args.settings = lib.recursiveUpdate defaultSettings {
  fonts.terminalSize = 14;
};

Asgard sets gaming.vrrOutput to its monitor this way, and Niflheim raises the terminal font size to 14. The template hosts use defaultSettings unchanged. For Asgard, the resolved settings are also passed into Home Manager, so system and user modules see the same values.

Theme familiesCopy Anchor Link

lib/themes.nix defines two families, Meowsoot (the default) and Kanagawa. An unknown family name fails evaluation. Each family provides:

• A light and a dark palette with the same semantic keys: background, foreground, muted, border, hover, selected, accents, link, status colours (error, warning, success, info), diff colours, syntax colours, and five surface shades (shade0 to shade4).
• apps: the theme names that applications use for their own built-in themes, such as Ghostty, Neovim, VS Code, and the GTK theme and package.
• niri: the window border gradient and inactive colour.

Most applications follow the system's light or dark appearance and receive both palettes.

Rendering templatesCopy Anchor Link

Configuration files that need theme colours are checked in as ordinary files with @placeholder@ markers. configLib.renderTemplate in lib/default.nix reads the file and substitutes each marker:

xdg.configFile."niri/config.kdl".text =
  configLib.renderTemplate {
    "@active-from@" = settings.theme.niri.activeFrom;
    "@active-to@" = settings.theme.niri.activeTo;
    "@inactive@" = settings.theme.niri.inactive;
  } ./config.kdl;

The same mechanism themes the Oh My Posh prompt, the Firefox and Tridactyl CSS, Noctalia's palette and font, and Niri's borders. The OpenCode theme, imv background, GTK settings, and Neovim (CONFIG_THEME_FAMILY) read the palette values directly. Asgard's Limine boot menu uses the Meowsoot dark colours.

To switch the whole setup to Kanagawa, change family in defaultSettings (or override theme for one host) and rebuild.