add iosevkaCustom to home.nix

stylix.nix

@@ -49,7 +49,44 @@
         name = config.stylix.fonts.monospace.name;
       };
       monospace = {
-        package = pkgs.iosevka;
+        package = (
+          pkgs.iosevka.override {
+            set = "Custom";
+            privateBuildPlan = ''
+                              [buildPlans.IosevkaCustom]
+              family = "Iosevka Custom"
+              spacing = "fontconfig-mono"
+              serifs = "slab"
+              noCvSs = true
+              exportGlyphNames = false
+
+                [buildPlans.IosevkaCustom.variants]
+                inherits = "ss12"
+
+              [buildPlans.IosevkaCustom.weights.Regular]
+              shape = 400
+              menu = 400
+              css = 400
+
+              [buildPlans.IosevkaCustom.weights.Bold]
+              shape = 700
+              menu = 700
+              css = 700
+
+              [buildPlans.IosevkaCustom.slopes.Upright]
+              angle = 0
+              shape = "upright"
+              menu = "upright"
+              css = "normal"
+
+              [buildPlans.IosevkaCustom.slopes.Italic]
+              angle = 9.4
+              shape = "italic"
+              menu = "italic"
+              css = "italic"
+            '';
+          }
+        );
         name = "Iosevka";
       };