@media (max-width: 500px) {
    html {
        background-image: url("http://www.weaverpotatoes.co.uk/wp-content/uploads/2018/02/Weaver-Harvester.jpg");
        background-position: top center;
        background-repeat: no-repeat;
        background-attachment: fixed;
        background-size: cover;
        height: 100%;
        overflow: hidden;
    }
    body.custom-background.safari.home.iphone {
        background-image: none;
        background-color: transparent;
        height:100%;
        overflow: scroll;
        -webkit-overflow-scrolling: touch;
    }
}