#visbleCanvas {
  position: absolute;
  top: 0;
  left: 0;
}
.thumbBox {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 200px;
  height: 200px;
  margin-top: -100px;
  margin-left: -100px;
  box-sizing: border-box;
  border: 1px solid #666666;
  box-shadow: 0 0 0 1000px rgba(0, 0, 0, 0.5);
  background: none repeat scroll 0% 0% transparent;
}