small fix

config/firefox/extensions.nix

@@ -5,7 +5,7 @@ args:
     firefox-addons = args.firefox-addons or null;
   in
     if firefox-addons != null then
-      with firefox-addons.packages.${args.pkgs.system}; [
+      with firefox-addons.packages.${args.pkgs.stdenv.hostPlatform.system}; [
         ublock-origin
         vimium
         cookies-txt

modules/claude-code.nix

@@ -4,14 +4,14 @@ with lib;
 
 let
   # Detect system architecture and select appropriate package
-  claudePackage = if pkgs.system == "aarch64-darwin" then
+  claudePackage = if pkgs.stdenv.hostPlatform.system == "aarch64-darwin" then
     claude-code.packages.aarch64-darwin.claude-code
-  else if pkgs.system == "x86_64-linux" then
+  else if pkgs.stdenv.hostPlatform.system == "x86_64-linux" then
     claude-code.packages.x86_64-linux.claude-code
-  else if pkgs.system == "aarch64-linux" then
+  else if pkgs.stdenv.hostPlatform.system == "aarch64-linux" then
     claude-code.packages.aarch64-linux.claude-code
   else
-    throw "Unsupported system for Claude Code: ${pkgs.system}";
+    throw "Unsupported system for Claude Code: ${pkgs.stdenv.hostPlatform.system}";
 
   # Default global permissions
   defaultPermissions = {

modules/fonts.nix

@@ -23,7 +23,7 @@ in
     nerd-fonts.jetbrains-mono
 
     # Ubuntu font family
-    ubuntu_font_family
+    ubuntu-classic
 
     # CJK fonts for proper Chinese/Japanese/Korean character display
     noto-fonts-cjk-sans     # Comprehensive CJK support