Hello,

Please provide me the link to the page, link to the wallpaper and device width.

Or you can add this code to Page Setting

@media screen and (min-width:768px){
.website-wrapper{
    background-image: url(PUT HERE URL OF THE IMAGE) !important;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}
.main-page-wrapper{
    background:transparent;
}
}

Best Regards