import streamlit as st

def main():
    """
    This is the main function that runs the Streamlit application.
    It sets up the title, displays a greeting, and takes user input.
    """
    st.set_page_config(page_title="My Simple Streamlit App", layout="centered")

    # --- Title and Header ---
    st.title("👋 Welcome to My First Streamlit App!")
    st.markdown("""
    This is a simple demonstration of what Streamlit can do.
    It's incredibly easy to build interactive web applications with just Python!
    """)

    st.write("---") # Horizontal line for separation

    # --- User Input Section ---
    st.header("Tell Us About Yourself!")
    user_name = st.text_input("What's your name?", "Guest") # Text input with a default value

    # Create a button
    if st.button("Say Hello!"):
        # Display a personalized greeting when the button is clicked
        st.success(f"Hello, {user_name}! It's great to see you here. 😊")
    else:
        st.info("Enter your name above and click 'Say Hello!'")

    st.write("---")

    # --- More Content (Optional) ---
    st.subheader("Explore More")
    st.write("Feel free to modify this code and experiment with other Streamlit widgets!")
    st.markdown("[Streamlit Documentation](https://docs.streamlit.io/)")

if __name__ == "__main__":
    main()