.ddfc-calculator {
    max-width: 600px;
    background: #f7f7f7;
    padding: 20px;
    border-radius: 12px;
    font-family: sans-serif;
}
.ddfc-calculator label {
    display: block;
    margin-bottom: 10px;
}
.ddfc-calculator input,
.ddfc-calculator select {
    width: 100%;
    padding: 8px;
    margin-top: 4px;
    margin-bottom: 10px;
}
.ddfc-calculator button {
    background-color: #2c3e50;
    color: white;
    padding: 10px;
    border: none;
    width: 100%;
    cursor: pointer;
    border-radius: 8px;
}
#result {
    margin-top: 20px;
    font-weight: bold;
}