Update app.py

app.py

@@ -72,7 +72,7 @@ def get_screenshot(chat,css_in,w,h,user_c,bot_c,background_c,font_c):
     print(user_c)
     if user_c:
         user_c=user_c.strip('""').strip("''")
-        html_user=css.replace("background: #367bb9; #user_c",f"background: {user_c};")
+        css=css.replace("background: #367bb9; #user_c",f"background: {user_c};")
     html_body=""
     for user,bot in chat:
         html_body += html_user.replace("$chat",user)