#cover {
  position:fixed;
  padding:0;
  margin:0;
  top:0;
  left:0;
  width:100%;
  height:100%;
  background:rgba(0,0,0,1)
}

#highlight {
  position:fixed;
  padding:0;
  margin:0;
  top:0;
  left:0;
  width:100%;
  height:100%;
  background:rgba(0,0,0,0.4)
}