@media (min-width: 768px) {
body {
background-image: url (одна картинка);
background-size: cover;
background-repeat: no-repeat;
overflow: hidden
width: 100% }
}
@media (min-width: 1200px) {
body {
background-image: url (другая картинка);
background-size: cover;
background-repeat: no-repeat;
overflow: hidden
width: 100% }
}