fix: bind to 0.0.0.0 on HF Spaces; move CSS to launch()

app.py

@@ -13,6 +13,7 @@ Usage:
 from __future__ import annotations
 
 import argparse
+import os
 import sys
 from dataclasses import asdict
 from pathlib import Path
@@ -103,8 +104,7 @@ def _retrieved_html(retrieved: list[dict]) -> str:
 
 
 def _build_app(bot: Chatbot) -> gr.Blocks:
-    with gr.Blocks(title="Multilingual Chatbot — AR/EN/FR/CS",
-                   css=CUSTOM_CSS) as demo:
+    with gr.Blocks(title="Multilingual Chatbot — AR/EN/FR/CS") as demo:
         gr.Markdown(
             "# Multilingual Chatbot\n"
             "**AR / EN / FR / CS** · Detects language → classifies intent → extracts entities "
@@ -191,15 +191,18 @@ def main() -> int:
                         help="Create a public Gradio share link.")
     parser.add_argument("--port", type=int, default=7860,
                         help="Local server port (default 7860).")
-    parser.add_argument("--host", type=str, default="127.0.0.1",
-                        help="Server host (default 127.0.0.1).")
+    parser.add_argument("--host", type=str,
+                        default=os.environ.get("GRADIO_SERVER_NAME", "127.0.0.1"),
+                        help="Server host (default 127.0.0.1 locally; HF Spaces sets "
+                             "GRADIO_SERVER_NAME=0.0.0.0 which is then used).")
     args = parser.parse_args()
 
     print("Loading models ...")
     bot = Chatbot()
     demo = _build_app(bot)
     demo.launch(server_name=args.host, server_port=args.port, share=args.share,
-                theme=gr.themes.Soft(primary_hue="indigo", secondary_hue="slate"))
+                theme=gr.themes.Soft(primary_hue="indigo", secondary_hue="slate"),
+                css=CUSTOM_CSS)
     return 0