body
{
  background-color:pink;
}


div.testaaa
{
  position: absolute;
  left: 100px;
  top:100px;
  width:200px;
  height:50px;
  border: 1px solid red;
}

@media all and (display-mode: standalone) {
  div.testaaa {
    display: none;
  }
}