app.py

import streamlit as st

st.set_page_config(page_title="Simple Calculator", page_icon="🧮", layout="centered")

# Custom CSS for modern look
st.markdown("""
    <style>
    .main {
        background-color: #f7f7f7;
    }
    .stButton button {
        border-radius: 8px;
        background-color: #4CAF50;
        color: white;
        padding: 10px 24px;
        margin: 10px 0px;
        font-size: 16px;
    }
    </style>
""", unsafe_allow_html=True)

# Title
st.title("🧮 Basic Calculator")

# User input
num1 = st.number_input("Enter first number", format="%.2f")
num2 = st.number_input("Enter second number", format="%.2f")

# Operation selection
operation = st.selectbox(
    "Select operation",
    ("Addition", "Subtraction", "Multiplication", "Division")
)

# Calculate button
if st.button("Calculate"):
    if operation == "Addition":
        result = num1 + num2
        st.success(f"Result: {result:.2f}")
    elif operation == "Subtraction":
        result = num1 - num2
        st.success(f"Result: {result:.2f}")
    elif operation == "Multiplication":
        result = num1 * num2
        st.success(f"Result: {result:.2f}")
    elif operation == "Division":
        if num2 != 0:
            result = num1 / num2
            st.success(f"Result: {result:.2f}")
        else:
            st.error("Error: Division by zero is not allowed.")