body {
    font-family: Arial, sans-serif;
    background: #f3f3f3;
    display: flex;
    justify-content: center;
    padding-top: 40px;
}

.calc-box {
    background: white;
    padding: 25px 30px;
    border-radius: 12px;
    width: 400px;
    text-align: center;
}

h2 {
    color: #333;
}

input,
select {
    width: 90%;
    padding: 10px;
    margin-bottom: 12px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 15px;
}

input:focus,
select:focus {
    border-color: #db1a1a;
    outline: none;
}

.btn {
    width: 95%;
    padding: 12px;
    background: #b10707;
    border: none;
    color: white;
    font-size: 16px;
    border-radius: 8px;
    cursor: pointer;
    margin-top: 5px;
    transition: 0.3s;
}

.btn:hover {
    background: #cc0000;
}

.resultado {
    margin-top: 20px;
    padding: 12px;
    background: #e8f3ff;
    border-left: 4px solid #b01524;
    font-size: 18px;
    border-radius: 6px;
    color: #004a99;
}