body {
background-image: url(images/background-photo.jpg);
  
background-position: center center;
 
background-repeat: no-repeat;
  
background-attachment: fixed;
  
background-size: cover;
  
background-color:#464646;
  
/* SHORTHAND CSS NOTATION
* background: url(background-photo.jpg) center center cover no-repeat fixed;
*/
}

@media only screen and (max-width: 767px) {
body {
background-image: url(images/background-photo-mobile-devices.jpg);
}
}