How to make background image fixed responsive working on actual mobile devices with simple css?

A blog or website background image not working on actual mobile devices.
Use css below

1. Left background image:

@media(max-width:480px){
body{
background-image: url("img.jpg");
background-repeat: no-repeat;
background-attachment: fixed;
background-position: top left;
background-size:350% auto;
}
}


Left background



2. Center background image:

@media(max-width:480px){
body{
background-image