#imgsizemark {
  position:absolute;
  top:-99999px;
  left:-99999px;
}
#imgsizemark:before{content:"Phone";}
@media (min-width: 768px) {
  #imgsizemark:before{content:"pad";}
}
@media (min-width: 992px) {
  #imgsizemark:before{content:"pc";}
}
@media (min-width: 1200px) {
  #imgsizemark:before{content:"pc";}
}