media (max-width: 768px) and (min-resolution: 144dpi),
(max-width: 768px) and (min-resolution: 1.5dppx) {
.preview {
background-image: url("img/mobile@2x.jpg");
background-size: 575px auto;
}
}
media (min-width: 768px) and (min-resolution: 144dpi),
(min-width: 768px) and (min-resolution: 1.5dppx) {
.preview {
background-image: url("img/desktop@2x.jpg");
background-size: 1150px auto;
}
}
все, разобрался, вот так сработало))