Add terminal transparency

terminal.nix

@@ -8,6 +8,6 @@
       name = "Monospace Regular";
       size = 12;
     };
-    extraConfig = "enable_auto_bell 0\nconfirm_os_window_close 0";
+    extraConfig = "enable_auto_bell 0\nconfirm_os_window_close 0\nbackground_opacity 0.8";
   };
 }