.YaoGan {
  position: absolute;
  background-size: 100% 100%;
  z-index: 9;
}
.YaoGan .control {
  position: absolute;
  display: block;
  z-index: 999;
  transition: opacity 280ms ease 0s;
  top: 50%;
  left: 50%;
}
.YaoGan .control .front {
  position: absolute;
  display: block;
  margin-left: -25px;
  margin-top: -25px;
  background: white;
  opacity: 0.5;
  border-radius: 50%;
  transition: none 0s ease 0s;
}