body {
    background: #f2f2f2;
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
    padding: 0;
}
.container {
    background: #fff;
    max-width: 400px;
    margin: 60px auto;
    padding: 30px 25px 35px 25px;
    border-radius: 10px;
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    text-align: center;
}
h1 {
    color: #2d3e50;
    margin-bottom: 20px;
}
label {
    display: block;
    margin-bottom: 10px;
    color: #444;
    font-weight: bold;
}
input[type="number"] {
    width: 100%;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 16px;
}
button {
    background: #4caf50;
    color: #fff;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.2s;
}
button:hover {
    background: #388e3c;
}
#resultado {
    margin-top: 20px;
    font-size: 18px;
    font-weight: bold;
}