home-manager extraCss option for more targets

[jamesbaw1]

Currently, it's quite difficult to add CSS on top of the CSS generated by Stylix. The main issue is when it comes to overwriting CSS rules, because the user-defined CSS (for example programs.waybar.style in home.nix) is applied before the CSS generated by Stylix.

Perhaps we could add an extraCss option to more (hopefully eventually all) targets, as it is already a feature for GTK, and would be as simple (I think?) as appending the text in the user-defined extraCss to the CSS that is already being applied to the target. For example:

programs.waybar.style =
  # ...
  + (if config.stylix.targets.waybar.extraCss then stylix.targets.waybar.extraCss else ""); # I don't think this code works, but I hope It's somewhat illustrative

This could also act as a band-aid solution to #429 and maybe some other feature requests concerning CSS, as users could simply overwrite existing CSS rules.

The other option may be to somehow get the user-defined programs.waybar.style to apply after Stylix's version, but I'm not an expert at nix, and I don't know how feasible this is. It's also not as universal a solution.

[danth]

There are mkBefore and mkAfter functions in lib. These change the order in which option definitions are merged; for example the two definitions "a" and mkBefore "b" would be guaranteed to merge as "ba".

If we add mkBefore to any CSS defined by Stylix, then we can guarantee that CSS added by the user will be applied later without needing to create another option.

[jamesbaw1]

So,

config = lib.mkIf (config.stylix.enable && config.stylix.targets.waybar.enable) {
    programs.waybar.style = # ...
};

would become

config = lib.mkIf (config.stylix.enable && config.stylix.targets.waybar.enable) lib.mkBefore {
    programs.waybar.style = # ...
};

?

I'm relatively new to the nix language, so sorry if I'm missing the obvious.

[danth]

I believe the mkBefore needs to go on the programs.waybar.style option specifically, so it should be programs.waybar.style = lib.mkBefore ...

[jamesbaw1]

Ah, okay. I'm still getting my setup in order, so it may take a while for me to submit a PR.