#topcontrol {
 width: 63px;
 height: 49px;
 background: #d1d3d3 url("/img/btn-up.png") center no-repeat;
 z-index:70;
}

@media screen and (max-width:600px) {
 #topcontrol {
  width: 47px;
  height: 37px;
  background-size: 47px 37px;
 }
}