@media only screen
  and (min-device-width: 375px) 
  and (max-device-width: 850px) 
  and (-webkit-min-device-pixel-ratio: 2) { 
 	.pdfview{
    top: 50px;
    left: 0;
    right: 0;
    bottom: 0;
    overflow: scroll;
    -webkit-overflow-scrolling: touch;
	} 
}