.section._calc {
    background: #F5F5F5;
}

.section._calc_result {
    padding-top: 30px;
}

.form-calc {
    max-width: 350px;
    margin: auto;
}

.form-calc .button {
    width: 100%;
}

.result {
    text-align: center;
}

.sum {
    font-weight: bold;
    font-size: 32px;
    line-height: 39px;
}