diff --git a/aider/main.py b/aider/main.py
index fdcea1df6..298754022 100644
--- a/aider/main.py
+++ b/aider/main.py
@@ -114,6 +114,12 @@ def main(args=None, input=None, output=None):
     )
 
     output_group = parser.add_argument_group("Output Settings")
+    output_group.add_argument(
+        "--dark-mode",
+        action="store_true",
+        help="Use colors suitable for a dark terminal background (default: False)",
+        default=False,
+    )
     output_group.add_argument(
         "--pretty",
         action="store_true",
@@ -251,6 +257,12 @@ def main(args=None, input=None, output=None):
     )
     args = parser.parse_args(args)
 
+    if args.dark_mode:
+        args.user_input_color = "#32FF32"
+        args.tool_output_color = "#ffffff"
+        args.assistant_output_color = "#00FFFF"
+        args.code_theme = "monokai"
+
     io = InputOutput(
         args.pretty,
         args.yes,