diff --git a/TalkHeal.py b/TalkHeal.py
index ca0d692..f218c6e 100644
--- a/TalkHeal.py
+++ b/TalkHeal.py
@@ -43,50 +43,122 @@ def show_signup_ui():
             st.session_state.show_signup = False
             st.rerun()
         else:
-            st.error(message)
-    st.markdown("Already have an account? [Login](#)", unsafe_allow_html=True)
-    if st.button("Go to Login"):
-        st.session_state.show_signup = False
-        st.rerun()
 
-if not st.session_state.authenticated:
-    if st.session_state.show_signup:
-        show_signup_ui()
-    else:
-        show_login_ui()
-else:
-    st.title(f"Welcome to TalkHeal, {st.session_state.user_name}! 💬")
-    st.markdown("Navigate to other pages from the sidebar.")
+import streamlit as st
+import streamlit_authenticator as stauth
+import time
+from core.utils import (
+    load_auth_config, 
+    load_css, 
+    apply_custom_css, 
+    load_google_fonts, 
+    get_ai_response, 
+    save_conversations,
+    load_conversations
+)
+from components.sidebar import render_sidebar
+from components.header import render_header
 
-    if st.button("Logout"):
-        for key in ["authenticated", "user_email", "user_name", "show_signup"]:
-            if key in st.session_state:
-                del st.session_state[key]
-        st.rerun()
+# --- Page and Session Initialization ---
+st.set_page_config(
+    page_title="TalkHeal", 
+    page_icon="favicon/favicon.ico", 
+    layout="wide",
+    initial_sidebar_state="expanded"
+)
 
-import google.generativeai as genai
-from core.utils import save_conversations, load_conversations
-from core.config import configure_gemini, PAGE_CONFIG
-from core.utils import get_current_time, create_new_conversation
-from css.styles import apply_custom_css
-from components.header import render_header
-from components.sidebar import render_sidebar
-from components.chat_interface import render_chat_interface, handle_chat_input
-from components.emergency_page import render_emergency_page
-from components.profile import apply_global_font_size
-
-
-# --- 1. INITIALIZE SESSION STATE ---
-if "chat_history" not in st.session_state:
-    st.session_state.chat_history = []
-if "conversations" not in st.session_state:
-    st.session_state.conversations = load_conversations()
-if "active_conversation" not in st.session_state:
-    st.session_state.active_conversation = -1
-if "show_emergency_page" not in st.session_state:
-    st.session_state.show_emergency_page = False
-if "sidebar_state" not in st.session_state:
-    st.session_state.sidebar_state = "expanded"
+load_css()
+apply_custom_css()
+load_google_fonts()
+
+# --- Authentication ---
+if 'authenticator' not in st.session_state:
+    config = load_auth_config()
+    st.session_state.authenticator = stauth.Authenticate(
+        config['credentials'],
+        config['cookie']['name'],
+        config['cookie']['key'],
+        config['cookie']['expiry_days'],
+        config['preauthorized']
+    )
+
+authenticator = st.session_state.authenticator
+name, authentication_status, username = authenticator.login('main')
+
+# --- Session State for Chat ---
+if "messages" not in st.session_state:
+    st.session_state.messages = []
+
+# --- Main Application Logic ---
+if authentication_status:
+    # Load user's conversation history once per session after login
+    if "conversations_loaded" not in st.session_state and username:
+        st.session_state.messages = load_conversations(username)
+        st.session_state.conversations_loaded = True
+
+    # Main app layout
+    col1, col2 = st.columns([1, 4])
+
+    with col1:
+        render_sidebar(authenticator)
+
+    with col2:
+        render_header()
+
+        # Display existing chat messages from session state
+        for message in st.session_state.messages:
+            with st.chat_message(message["role"]):
+                st.markdown(message["content"])
+
+        # Handle new chat input from the user
+        if prompt := st.chat_input("Share your thoughts..."):
+            # Add user message to session state and display it
+            st.session_state.messages.append({"role": "user", "content": prompt})
+            with st.chat_message("user"):
+                st.markdown(prompt)
+
+            # Generate and display AI response
+            with st.chat_message("assistant"):
+                with st.spinner("TalkHeal is thinking..."):
+                    # Define the system prompt for the AI
+                    system_prompt = (
+                        "You are TalkHeal, a compassionate and supportive AI mental health companion. "
+                        "Your goal is to provide a safe, non-judgmental space for users to share their thoughts and feelings. "
+                        "Respond with empathy, offer encouragement, and gently guide the conversation. "
+                        "Do not provide medical advice, diagnoses, or treatment plans. "
+                        "If a user seems to be in crisis, strongly encourage them to seek help from a professional."
+                    )
+                    
+                    # Create a formatted history for the AI prompt
+                    chat_history_for_prompt = "\n".join(
+                        [f'{m["role"]}: {m["content"]}' for m in st.session_state.messages]
+                    )
+                    
+                    try:
+                        # Call the AI model
+                        ai_response = get_ai_response(
+                            f"{system_prompt}\n\n{chat_history_for_prompt}\nuser: {prompt}\nassistant:",
+                            "gemini-1.5-flash"
+                        )
+                        
+                        # Display the AI response
+                        st.markdown(ai_response)
+                        
+                        # Add AI response to session state
+                        st.session_state.messages.append({"role": "assistant", "content": ai_response})
+                        
+                        # Save the updated conversation history
+                        if username:
+                            save_conversations(username, st.session_state.messages)
+
+                    except Exception as e:
+                        error_message = f"Sorry, an error occurred: {e}"
+                        st.error(error_message)
+                        # Add an error message to the chat for user visibility
+                        st.session_state.messages.append({"role": "assistant", "content": "I'm having trouble responding right now. Please try again."})
+
+if "palette_name" not in st.session_state:
+    st.session_state.palette_name = "Light"
 if "mental_disorders" not in st.session_state:
     st.session_state.mental_disorders = [
         "Depression & Mood Disorders", "Anxiety & Panic Disorders", "Bipolar Disorder",
@@ -151,6 +223,7 @@ def get_tone_prompt():
 else:
     with main_area:
         render_header()
+        render_theme_toggle()
         st.markdown(f"""
 <div style="text-align: center; margin: 20px 0;">
     <h3>🗣️ Current Chatbot Tone: <strong>{st.session_state['selected_tone']}</strong></h3>
@@ -170,4 +243,4 @@ def get_tone_prompt():
     }
     setTimeout(scrollToBottom, 100);
 </script>
-""", unsafe_allow_html=True) 
\ No newline at end of file
+""", unsafe_allow_html=True)
\ No newline at end of file
diff --git a/components/sidebar.py b/components/sidebar.py
index e684be2..da017fe 100644
--- a/components/sidebar.py
+++ b/components/sidebar.py
@@ -347,16 +347,20 @@ def render_sidebar():
             </div>
             """.format(current_theme['name']), unsafe_allow_html=True)
 
-            # Theme toggle button with better styling
-            button_text = "🌙 Dark Mode" if not is_dark else "☀️ Light Mode"
-            button_color = "primary" if not is_dark else "secondary"
+            # Theme toggle button with ultra-fast performance
+            button_text = "🌙 Dark" if not is_dark else "☀️ Light"
+            
+            # Use a unique key that includes current state and version for optimal performance
+            sidebar_button_key = f"sidebar_theme_toggle_{is_dark}_{st.session_state.get('sidebar_theme_version', 0)}"
 
             if st.button(
                 button_text,
-                key="sidebar_theme_toggle",
+                key=sidebar_button_key,
                 use_container_width=True,
-                type=button_color
+                help="Toggle Light/Dark Mode"
             ):
+                # Increment version for faster re-renders
+                st.session_state.sidebar_theme_version = st.session_state.get('sidebar_theme_version', 0) + 1
                 toggle_theme()
 
         # Quizzes expander (no longer contains nested expander)
diff --git a/components/theme_toggle.py b/components/theme_toggle.py
index e4e2dd1..6fe6d65 100644
--- a/components/theme_toggle.py
+++ b/components/theme_toggle.py
@@ -2,7 +2,7 @@
 from core.theme import toggle_theme, get_current_theme
 
 def render_theme_toggle():
-    """Render the theme toggle button in the top right corner."""
+    """Render the theme toggle button with optimized performance."""
     current_theme = get_current_theme()
     is_dark = current_theme["name"] == "Dark"
     
@@ -12,54 +12,71 @@ def render_theme_toggle():
         col1, col2, col3 = st.columns([0.7, 0.2, 0.1])
         
         with col3:
-            # Theme toggle button
-            button_text = "🌙 Dark Mode" if is_dark else "☀️ Light Mode"
-            button_color = "primary" if is_dark else "secondary"
+            # Theme toggle button with ultra-fast response
+            button_text = "🌙 Dark" if not is_dark else "☀️ Light"
             
+            # Use a unique key that includes current state to prevent conflicts
+            button_key = f"theme_toggle_{is_dark}_{st.session_state.get('theme_version', 0)}"
+            
+            # Add immediate visual feedback with custom styling
             if st.button(
                 button_text,
-                key="theme_toggle",
+                key=button_key,
                 help="Toggle Light/Dark Mode",
-                use_container_width=True,
-                type=button_color
+                use_container_width=True
             ):
+                # Increment theme version for faster key generation
+                st.session_state.theme_version = st.session_state.get('theme_version', 0) + 1
                 toggle_theme()
         
-        # Add some custom CSS to style the toggle button
+        # Ultra-optimized CSS with hardware acceleration
         st.markdown("""
         <style>
-        /* Theme toggle button styling - consistent with sidebar */
-        [data-testid="stButton"] > button[key="theme_toggle"] {
+        /* Theme toggle button styling - maximum performance */
+        [data-testid="stButton"] > button[key*="theme_toggle"] {
             background: var(--light-transparent-bg) !important;
             color: var(--text-primary) !important;
             border: 1px solid var(--light-transparent-border) !important;
             border-radius: var(--radius) !important;
-            padding: 12px 16px !important;
+            padding: 10px 14px !important;
             font-weight: 600 !important;
-            transition: all 0.2s ease !important;
+            transition: all 0.08s ease-out !important;
             font-family: 'Inter', sans-serif !important;
-            box-shadow: 0 2px 8px var(--shadow) !important;
-            backdrop-filter: blur(5px) !important;
+            box-shadow: 0 2px 6px var(--shadow) !important;
+            backdrop-filter: blur(2px) !important;
             white-space: nowrap !important;
             text-overflow: ellipsis !important;
             overflow: hidden !important;
-            min-height: 44px !important;
+            min-height: 40px !important;
             display: flex !important;
             align-items: center !important;
             justify-content: center !important;
-            font-size: 0.9em !important;
-            line-height: 1.2 !important;
+            font-size: 0.85em !important;
+            line-height: 1.1 !important;
             word-break: keep-all !important;
+            will-change: transform, background, box-shadow !important;
+            transform: translateZ(0) !important;
+            backface-visibility: hidden !important;
+            -webkit-font-smoothing: antialiased !important;
+            -moz-osx-font-smoothing: grayscale !important;
         }
         
-        [data-testid="stButton"] > button[key="theme_toggle"]:hover {
+        [data-testid="stButton"] > button[key*="theme_toggle"]:hover {
             background: var(--light-transparent-bg-hover) !important;
-            transform: translateY(-1px) !important;
-            box-shadow: 0 4px 12px var(--shadow-lg) !important;
+            color: var(--button-hover-text) !important;
+            border-color: var(--primary-color) !important;
+            border-width: 2px !important;
+            transform: translateY(-1px) scale(1.02) translateZ(0) !important;
+            box-shadow: 0 4px 10px var(--shadow-lg) !important;
+        }
+
+        [data-testid="stButton"] > button[key*="theme_toggle"]:active {
+            transform: translateY(0) scale(1.0) translateZ(0) !important;
+            transition: all 0.05s ease-out !important;
         }
         
         /* Ensure button text doesn't wrap */
-        [data-testid="stButton"] > button[key="theme_toggle"] span {
+        [data-testid="stButton"] > button[key*="theme_toggle"] span {
             white-space: nowrap !important;
             overflow: hidden !important;
             text-overflow: ellipsis !important;
diff --git a/core/theme.py b/core/theme.py
index a52edc3..66f1e3a 100644
--- a/core/theme.py
+++ b/core/theme.py
@@ -237,13 +237,41 @@ def get_current_theme() -> Dict[str, Any]:
         return palette
 
 def set_palette(palette_name: str):
+    # Add light throttling to prevent rapid successive calls
+    import time
+    current_time = time.time()
+    last_palette_time = st.session_state.get("last_palette_change", 0)
+    
+    # Only allow palette change every 50ms to prevent spam (reduced from 200ms)
+    if current_time - last_palette_time < 0.05:
+        return
+    
+    if st.session_state.get("palette_name") == palette_name:
+        return  # No change needed
+    
+    st.session_state.last_palette_change = current_time
     st.session_state.palette_name = palette_name
     st.session_state.theme_changed = True
+    
+    # Force immediate rerun for faster response
     st.rerun()
 
 def toggle_theme():
-    """Toggle between light and dark themes."""
+    """Toggle between light and dark themes with optimized performance."""
     initialize_theme_state()
+    
+    # Add light throttling to prevent rapid successive calls
+    import time
+    current_time = time.time()
+    last_toggle_time = st.session_state.get("last_theme_toggle", 0)
+    
+    # Only allow theme toggle every 50ms to prevent spam (reduced from 200ms)
+    if current_time - last_toggle_time < 0.05:
+        return
+    
+    st.session_state.last_theme_toggle = current_time
     st.session_state.dark_mode = not st.session_state.dark_mode
     st.session_state.theme_changed = True
+    
+    # Force immediate rerun for faster response
     st.rerun() 
\ No newline at end of file
diff --git a/core/utils.py b/core/utils.py
index 97f3a0a..238d961 100644
--- a/core/utils.py
+++ b/core/utils.py
@@ -1,3 +1,35 @@
+import json
+import os
+
+# Directory to store conversation files
+CONVERSATIONS_DIR = "conversations"
+if not os.path.exists(CONVERSATIONS_DIR):
+    os.makedirs(CONVERSATIONS_DIR)
+
+def save_conversations(username, messages):
+    """Saves a user's conversation history to a JSON file."""
+    if not username:
+        return
+    file_path = os.path.join(CONVERSATIONS_DIR, f"{username}_chat.json")
+    try:
+        with open(file_path, "w") as f:
+            json.dump(messages, f, indent=4)
+    except Exception as e:
+        print(f"Error saving conversation for {username}: {e}")
+
+def load_conversations(username):
+    """Loads a user's conversation history from a JSON file."""
+    if not username:
+        return []
+    file_path = os.path.join(CONVERSATIONS_DIR, f"{username}_chat.json")
+    if os.path.exists(file_path):
+        try:
+            with open(file_path, "r") as f:
+                return json.load(f)
+        except (json.JSONDecodeError, Exception) as e:
+            print(f"Error loading conversation for {username}: {e}")
+            return []
+    return []
 from datetime import datetime, timedelta, timezone
 import streamlit as st
 import re
diff --git a/css/styles.py b/css/styles.py
index 18ec9cd..0204f6e 100644
--- a/css/styles.py
+++ b/css/styles.py
@@ -1,14 +1,36 @@
 import streamlit as st
 import base64
+import hashlib
 
 def get_base64_of_bin_file(bin_file):
     with open(bin_file, 'rb') as f:
         data = f.read()
     return base64.b64encode(data).decode()
 
+@st.cache_data(ttl=600, show_spinner=False)  # Cache for 10 minutes, no spinner
+def _generate_css_hash(theme_config):
+    """Generate a hash of the theme configuration for caching."""
+    # Only hash essential theme properties for better cache hits
+    essential_props = ['name', 'primary', 'background_image', 'text_primary', 'light_transparent_bg']
+    theme_subset = {k: v for k, v in theme_config.items() if k in essential_props}
+    theme_str = str(sorted(theme_subset.items()))
+    return hashlib.md5(theme_str.encode()).hexdigest()
+
 def apply_custom_css():
     from core.theme import get_current_theme
     theme_config = get_current_theme()
+    
+    # Check if CSS needs to be regenerated using faster hash comparison
+    css_hash = _generate_css_hash(theme_config)
+    last_css_hash = st.session_state.get("last_css_hash", "")
+    
+    # Skip CSS regeneration if theme hasn't meaningfully changed
+    if css_hash == last_css_hash and not st.session_state.get("theme_changed", False):
+        return
+    
+    # Update cache state
+    st.session_state.last_css_hash = css_hash
+    st.session_state.theme_changed = False
     theme_overrides = {
         'primary': '#6366f1',
         'primary_light': '#818cf8',
@@ -56,6 +78,10 @@ def apply_custom_css():
             --border-light: {theme_config['border_light']};
             --shadow: {theme_config['shadow']};
             --shadow-lg: {theme_config['shadow_lg']};
+            --light-transparent-bg: {theme_config['light_transparent_bg']};
+            --light-transparent-bg-hover: {theme_config['light_transparent_bg_hover']};
+            --light-transparent-border: {theme_config['light_transparent_border']};
+            --button-hover-text: {theme_config['primary_dark']};
             --radius: 12px;
             --radius-lg: 22px;
             --radius-xl: 36px;
@@ -378,53 +404,81 @@ def apply_custom_css():
             box-shadow: 0 6px 16px rgba(99, 102, 241, 0.4) !important;
         }}
 
-        /* Theme toggle button styling */
-        .stApp button[key="theme_toggle"],
-        .stApp button[key="sidebar_theme_toggle"] {{
+        /* Theme toggle button styling - ultra-fast optimized */
+        .stApp button[key*="theme_toggle"] {{
             white-space: nowrap !important;
             text-overflow: ellipsis !important;
             overflow: hidden !important;
-            min-height: 44px !important;
+            min-height: 40px !important;
             display: flex !important;
             align-items: center !important;
             justify-content: center !important;
-            font-size: 0.9em !important;
-            line-height: 1.2 !important;
+            font-size: 0.85em !important;
+            line-height: 1.1 !important;
             word-break: keep-all !important;
             background: var(--light-transparent-bg) !important;
             color: var(--text-primary) !important;
             border: 1px solid var(--light-transparent-border) !important;
             border-radius: var(--radius) !important;
-            padding: 12px 16px !important;
+            padding: 10px 14px !important;
             font-weight: 600 !important;
-            transition: all 0.2s ease !important;
+            transition: all 0.1s ease-out !important;
             font-family: 'Inter', sans-serif !important;
-            box-shadow: 0 2px 8px var(--shadow) !important;
-            backdrop-filter: blur(5px) !important;
+            box-shadow: 0 2px 6px var(--shadow) !important;
+            backdrop-filter: blur(3px) !important;
+            will-change: transform, background, box-shadow !important;
+            transform: translateZ(0) !important; /* Force hardware acceleration */
+            backface-visibility: hidden !important; /* Prevent flickering */
         }}
 
-        /* General button styling */
+        .stApp button[key*="theme_toggle"]:hover {{
+            background: var(--light-transparent-bg-hover) !important;
+            color: var(--button-hover-text) !important;
+            border-color: var(--primary-color) !important;
+            border-width: 2px !important;
+            transform: translateY(-1px) scale(1.02) translateZ(0) !important;
+            box-shadow: 0 4px 10px var(--shadow-lg) !important;
+        }}
+
+        .stApp button[key*="theme_toggle"]:active {{
+            transform: translateY(0) scale(1.0) translateZ(0) !important;
+            transition: all 0.05s ease-out !important;
+        }}
+
+        /* General button styling - ultra-fast transitions */
         button, .stButton > button, .stDownloadButton > button, .stFormSubmitButton > button {{
             background: var(--glass-effect) !important;
             background-color: var(--light-transparent-bg, rgba(255,255,255,0.13)) !important;
-            color: #000000 !important;
+            color: var(--text-primary) !important;
             border: 1px solid var(--light-transparent-border, rgba(255,255,255,0.16)) !important;
             border-radius: var(--radius) !important;
             padding: 14px 22px !important;
             font-weight: 600 !important;
             font-family: 'Poppins',sans-serif !important;
             box-shadow: 0 3px 12px rgba(0,0,0,0.08) !important;
-            transition: var(--transition,.21s cubic-bezier(.5,.08,.37,1.11)) !important;
+            transition: all 0.1s cubic-bezier(0.4, 0.0, 0.2, 1) !important;
+            will-change: transform, background, box-shadow !important;
+            transform: translateZ(0) !important; /* Force hardware acceleration */
+            backface-visibility: hidden !important; /* Prevent flickering */
         }}
         
-        /* General button hover effects */
+        /* General button hover effects - ultra-fast with proper contrast */
         button:hover, .stButton > button:hover,
         .stDownloadButton > button:hover,
         .stFormSubmitButton > button:hover {{
             border-color: var(--primary-color) !important;
             border-width: 2px !important;
-            transform: translateY(-2px) scale(1.04) !important;
-            box-shadow: 0 4px 16px rgba(99,102,241,0.2) !important;
+            color: var(--button-hover-text) !important;
+            transform: translateY(-1px) scale(1.02) translateZ(0) !important;
+            box-shadow: 0 4px 14px rgba(99,102,241,0.2) !important;
+        }}
+
+        /* Button active state for instant feedback */
+        button:active, .stButton > button:active,
+        .stDownloadButton > button:active,
+        .stFormSubmitButton > button:active {{
+            transform: translateY(0) scale(1.0) translateZ(0) !important;
+            transition: all 0.05s ease-out !important;
         }}
         
         /* Primary buttons */