.header {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-size: cover;
    background-position: center;
    text-align: center;
    padding: 320px 0;
    position: relative;
}

@media (min-width: 768px) {
    .header {
        background-attachment: fixed;
    }
}

.header::before {
    content: "";
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 1;
}