.box {
    width: 320px;
    border: 1px solid #0000ff;
    padding: 15px;
    font-family: Arial, sans-serif;
}
h3 {
    text-align: center;
    margin-top: 0;
}
.form-group {
    margin-bottom: 8px;
}
label {
    display: inline-block;
    width: 75px;
}
input[type="text"] {
    width: 180px;
}
.result {
    margin-top: 10px;
}