.ec-calculator {
    max-width: 400px;
    background: #f4f4f4;
    padding: 20px;
    border-radius: 10px;
    font-family: Arial, sans-serif;
}
.ec-calculator h3 {
    margin-bottom: 15px;
}
#ec-result {
    margin-top: 15px;
    font-weight: bold;
    color: green;
}