Put the following snippets in your configuration.nix
.
services.xserver.displayManager.slim = {
enable = true;
theme = pkgs.fetchurl {
url = "https://github.com/edwtjo/nixos-black-theme/archive/v1.0.tar.gz";
sha256 = "13bm7k3p6k7yq47nba08bn48cfv536k4ipnwwp1q1l2ydlp85r9d";
};
};
services.xserver.displayManager.lightdm = {
enable = true;
greeter.tiny = {
enable = true;
extraConfig = let
black = import (builtins.fetchTarball {
url = "https://github.com/edwtjo/nixos-black-theme/archive/v1.1.1.tar.gz";
sha256 = "16qmz1c22arn614zfrfn9a6y7k091227ghvnm97xn8nvgd11hlhz";
});
in
black.lightdm-tiny;
};
};