body 
{
 background-image: url("desktop.png");
 background-repeat: no-repeat;
 background-color: #f5e729;
 background-size: 50%;
 background-attachment: fixed;
 background-position: center;
}

@media only screen and (max-width: 1000px) {
    body {
        background-image: url("mobile.png");
        background-repeat: no-repeat;
        background-size: 80%;
        background-color: #f5e729;
  	background-attachment: fixed;
  	background-position: center;
    }
  }