#curtainleft {
  background-image: url('opensliden.png');
  background-size:100% 100%;
  position: absolute;
  display: block;
  height:100%;
  opacity: 0.5;
  transition: 27.0s;
  animation-timing-function: linear;
  background-position: center;
  border-radius: 25px;
  -moz-border-radius: 25px;
  -webkit-border-radius: 25px;
}

#curtainright {
  background-image: url('opensliden2.png');
  background-size:100% 100%;
  position: absolute;
  display: block;
  height:100%;
  opacity: 0.5;
  transition: 27.0s;
  animation-timing-function: linear;
  background-position: center;
  border-radius: 25px;
  -moz-border-radius: 25px;
  -webkit-border-radius: 25px;
}

#curtainleft {
  background-size:200% 100%;
  width:200%;
  left:-50%;
  top:0;
  box-shadow: 10px 0 20px black;
}

#curtainright {
  background-size:200% 100%;
  width:200%;
  right:-50%;
  top:0;
  box-shadow: -10px 0 20px black;
}