Redo overlays setup. Move to "final: prev:". Provide TST as overlay

overlays/default.nix

@@ -1,30 +1,17 @@
 { sources, system ? builtins.currentSystem, ... }@args:
 
 let
-  overlay = self: super: {
-    nur = import sources.nur {
-      nurpkgs = self;
-      pkgs = self;
-    };
-    anicca = self.callPackage sources.anicca {};
-    rustfmt = super.rustfmt.overrideAttrs ({ patches ? [ ], ... }: {
-      patches = patches ++ [
-        # Adds an option variant that merges all use statements into a single block.
-        # Taken from https://github.com/rust-lang/rustfmt/pull/4680
-        ./Implement-One-option-for-imports_granularity-4669.patch
-      ];
-    });
-    linuxPackagesFor = kernel: (super.linuxPackagesFor kernel).extend (_: ksuper: {
-      zfsUnstable = ksuper.zfsUnstable.overrideAttrs (old: { meta = old.meta // { broken = false; }; });
-    });
-  };
   pkgs = import sources.nixpkgs {
     overlays = [
-      (import (sources.arcexprs + "/overlay.nix"))
-      (import (sources.katexprs + "/overlay.nix"))
+      (import ./nur { inherit sources; })
       (import sources.emacs-overlay)
-      overlay
-    ];
+      (import ./rustfmt)
+      (import ./firefox-tst)
+    ] ++ (map (path: import "${path}/overlay.nix") [
+      sources.arcexprs
+      sources.katexprs
+      sources.anicca
+    ]);
     config = {
       allowUnfree = true;
       permittedInsecurePackages = [
@@ -33,4 +20,4 @@ let
     };
   };
 in
-pkgs
+  pkgs

overlays/firefox-tst/default.nix

@@ -0,0 +1,21 @@
+final: prev: {
+  firefox-tst = final.callPackage ({ stdenv, sass }: { base16 }:
+
+  stdenv.mkDerivation ({
+    pname = "firefox-tst-css";
+    version = "0.0.1";
+
+    phases = [ "buildPhase" ];
+
+    src = ./tst.sass;
+
+    buildInputs = [
+      sass
+    ];
+
+    buildPhase = ''
+      substituteAll $src firefox-tst-substituted.sass
+      sass firefox-tst-substituted.sass $out --sourcemap=none --style expanded
+    '';
+  } // base16)) {};
+}

overlays/firefox-tst/tst.sass

@@ -0,0 +1,115 @@
+// Colours
+$base00: @base00@
+$base01: @base01@
+$base02: @base02@
+$base03: @base03@
+$base04: @base04@
+$base05: @base05@
+$base06: @base06@
+$base07: @base07@
+$base08: @base08@
+$base09: @base09@
+$base0A: @base0A@
+$base0B: @base0B@
+$base0C: @base0C@
+$base0D: @base0D@
+$base0E: @base0E@
+$base0F: @base0F@
+// Fonts
+$font_0: "Cozette"
+$font_1: "monospace !important"
+
+*
+  font-family: $font_0, $font_1
+
+#tabbar
+  margin-top: calc(var(--pinned-tabs-area-size) - .15em)
+  position: absolute
+  border: none !important
+  overflow-y: scroll !important
+  margin-left: -.5em
+  background-color: $base00 !important
+  border-right: 1px solid $base01
+    box-shadow: none !important
+
+#tabbar-container
+  background-color: $base00 !important
+  border-right: 1px solid $base01
+    box-shadow: none !important
+
+.tab
+  background-color: $base01
+  color: $base05 !important
+    box-shadow: none !important
+  margin: 0.125em
+    border-radius: 0.125em
+  .twisty
+    margin-left: -16px
+  .highlighter::before
+    display: none
+
+  &.pinned
+    background-color: $base0D
+    color: $base07 !important
+    .twisty
+      margin-left: -16px
+
+    .label
+      margin-left: 7px
+
+
+  .label
+    margin-left: 7px
+    margin: 0.25em
+
+  .closebox
+    visibility: collapse
+
+  .favicon
+    margin-left: 0.25em
+
+  &:hover
+    background-color: $base0C !important
+    color: $base07 !important
+
+  &.discarded
+    background-color: $base00
+    color: $base02 !important
+    &:hover
+      background-color: $base01 !important
+      color: $base03 !important
+
+
+  &.active
+    background-color: $base0D
+    color: $base07 !important
+    &:hover
+      background-color: $base0D !important
+
+
+  &.muted
+    opacity: 0.5
+
+  &.sound-playing .label
+    background: linear-gradient(to right, #6666ff, #0099ff , #00ff00, #ff3399, #6666ff)
+        background-clip: text
+    color: transparent
+    animation: rainbow_animation 3s linear infinite
+    animation-direction: alternate-reverse
+    background-size: 400% 100%
+
+.sound-button::before
+  display: none !important
+
+.newtab-button
+  display: none
+
+
+@keyframes rainbow_animation
+  0%
+    background-position: 0 0
+
+  100%
+    background-position: 100% 0
+
+

overlays/nur/default.nix

@@ -0,0 +1,6 @@
+{ sources }: final: prev: {
+  nur = import sources.nur {
+    nurpkgs = final;
+    pkgs = final;
+  };
+}

overlays/rustfmt/default.nix

@@ -0,0 +1,9 @@
+final: prev: {
+  rustfmt = prev.rustfmt.overrideAttrs ({ patches ? [ ], ... }: {
+    patches = patches ++ [
+      # Adds an option variant that merges all use statements into a single block.
+      # Taken from https://github.com/rust-lang/rustfmt/pull/4680
+      ./Implement-One-option-for-imports_granularity-4669.patch
+    ];
+  });
+}

overlays/zfsUnstable/default.nix

@@ -0,0 +1,5 @@
+final: prev: {
+    linuxPackagesFor = kernel: (final.linuxPackagesFor kernel).extend (_: kfinal: {
+      zfsUnstable = kfinal.zfsUnstable.overrideAttrs (old: { meta = old.meta // { broken = false; }; });
+    });
+}