attempt to fix UI issue

fix info: create a row containing the chat interface and initially makes it invisible. When a PDF file is uploaded, the row becomes visible, showing the chat interface.

app.py

@@ -114,15 +114,15 @@ with gr.Blocks(title="PDF Chatbot") as demo:
             interactive=True
         )
 
-    chat_interface = gr.ChatInterface(
-        fn=chatbot.chat_with_pdf,
-        chatbot=gr.Chatbot(type="messages"),
-        textbox=gr.Textbox(placeholder="Type your question here...", scale=7),
-        examples=[["What is the main topic of the document?"], ["Summarize the key findings."], ["Who are the authors?"]],
-        title="Chat Interface",
-        theme="soft",
-        visible=False
-    )
+    with gr.Row(visible=False) as chat_row:
+        chat_interface = gr.ChatInterface(
+            fn=chatbot.chat_with_pdf,
+            chatbot=gr.Chatbot(type="messages"),
+            textbox=gr.Textbox(placeholder="Type your question here...", scale=7),
+            examples=[["What is the main topic of the document?"], ["Summarize the key findings."], ["Who are the authors?"]],
+            title="Chat Interface",
+            theme="soft"
+        )
 
     def process_and_show_chat(file):
         chatbot.process_pdf(file)
@@ -131,7 +131,7 @@ with gr.Blocks(title="PDF Chatbot") as demo:
     file_upload_input.upload(
         fn=process_and_show_chat,
         inputs=[file_upload_input],
-        outputs=[chat_interface, file_upload_input]
+        outputs=[chat_row, file_upload_input]
     )
 
 demo.launch()