{ lib, stdenvNoCC, fetchFromGitHub, writeText }:
let
  pname = "firefox-gx";
  version = "8.5";

  custom-menu = writeText "menu" "${builtins.readFile ./ogx_menu.css}";
  custom-sidebar = writeText "sidebar" "${builtins.readFile ./ogx_left-sidebar.css}";
in
stdenvNoCC.mkDerivation {
  inherit pname version;

  src = fetchFromGitHub {
    owner = "Godiesc";
    repo = pname;
    rev = "v.${version}";
    sha256 = "sha256-llffq16PZz5GxkLIJDeWN1d04SCCJFqwCLzOrxgwhYI=";
  };

  installPhase = ''
    # Personal changes
    sed -i 's/var(--fuchsia))/var(--purple))/' ./chrome/components/ogx_root-personal.css

    # Fix new tab background for nix
    substituteInPlace ./chrome/components/ogx_root-personal.css \
      --replace '../images/newtab/wallpaper-dark.png' "$out/chrome/images/newtab/private-dark.png"

    # TODO: make patch instead
    cp -a ${custom-menu} ./chrome/components/ogx_menu.css
    cp -a ${custom-sidebar} ./chrome/components/ogx_left-sidebar.css

    mkdir -p $out
    cp -r ./* $out
  '';

  meta = with lib; {
    description = "Firefox Theme CSS to Opera GX Lovers ";
    homepage = "https://github.com/Godiesc/firefox-gx";
    license = licenses.mspl;
  };
}