* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', sans-serif;
    background-color: #f4f4f4;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    flex-direction: column;
}

.container h1 {
    font-size: 2.5rem;
    margin-bottom: 20px;
}

.container h2 {
    font-size: 2rem;
    color: blueviolet;
    margin-bottom: 20px;
}


#operation {
    padding: 10px;
    width: 200px;
    margin-bottom: 20px;
}

input[type="number"] {
    padding: 10px;
    width: 200px;
    margin-bottom: 20px;
}

button {
    padding: 10px;
    width: 200px;
    background-color: #333;
    color: #fff;
    border: none;
    cursor: pointer;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);   
}   

button:hover {
    background-color: #555;
}