@media only screen and (-webkit-min-device-pixel-ratio:2) and (max-width:768px) and (min-width:321px),not all,only screen and (max-width:768px) and (-webkit-min-device-pixel-ratio:2) and (min-width:321px),only screen and (max-width:768px) and (min-resolution:192dpi) and (min-width:321px),only screen and (max-width:768px) and (min-resolution:2dppx) and (min-width:321px){
    /*some code here*/
}