body {
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
    display: flex;
    height: 100vh;
    align-items: center;
    justify-content: center;
}

.calculatrice {
    background: rgb(255, 255, 255);
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
    text-align: center;
}

.calculatrice input,
.calculatrice select,
.calculatrice button {
    margin: 10px;
    padding: 10px;
    font-size: 18px;
}

.resultat {
    margin-top: 20px;
    font-weight: bold;
    color: green;
}