nix flake add systems input

flake.nix

@@ -1,23 +1,39 @@
 {
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
-    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs = {
+      url = "github:NixOS/nixpkgs/nixos-unstable";
+    };
+    flake-parts = {
+      url = "github:hercules-ci/flake-parts";
+      inputs.nixpkgs-lib.follows = "nixpkgs";
+    };
+    systems = {
+      url = "github:nix-systems/default";
+    };
   };
 
-  outputs = inputs@{ nixpkgs, flake-parts, ... }:
-    flake-parts.lib.mkFlake { inherit inputs; } {
-      systems = [ "x86_64-linux" "aarch64-linux" ];
+  outputs = inputs @ {
+    nixpkgs,
+    flake-parts,
+    ...
+  }:
+    flake-parts.lib.mkFlake {inherit inputs;} {
+      systems = import inputs.systems;
 
-      perSystem = { pkgs, system, ... }: {
+      perSystem = {
+        pkgs,
+        system,
+        ...
+      }: {
         devShells.default =
-          pkgs.mkShell { packages = with pkgs; [ marp-cli ]; };
+          pkgs.mkShell {packages = with pkgs; [marp-cli];};
 
         packages.slides = pkgs.stdenvNoCC.mkDerivation {
           name = "slides";
 
           src = ./docs;
           dontUnpack = true;
-          buildInputs = with pkgs; [ marp-cli ];
+          buildInputs = with pkgs; [marp-cli];
 
           buildPhase = ''
             marp --html $src/slides.md --allow-local-files -o slides.html
@@ -32,4 +48,3 @@
       };
     };
 }
-