.bookcover
{
   box-shadow: 10px 10px 5px #888888;
}

.circle
{
  width:60px;
  height:60px;
  box-shadow: 3px 3px 6px #333333; 
  border-radius:50%;
  position: absolute;
  right: 50%;
  margin-right:-30px;
  bottom: 10px;
  -webkit-transition:all 0.2s linear;
  -moz-transition:all 0.2s linear;
  -ms-transition:all 0.2s linear;
  transition:all 0.2s linear;
}
.first_circle
{
  z-index: 4;
  background-color:#db4531;
  background-image: url(http://localhost:9080/hdwpbooks/images/button_buy.png);
  background-size:cover;
}
.second_circle
{
  z-index: 3;
//  background-image: url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/173024/rbnbrd.png);
  background-image: url(http://localhost:9080/hdwpbooks/images/button_amazon2.png);
  background-size:cover;
}
.third_circle
{
  z-index: 2;
//  background-image: url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/173024/jonathanlarradet.png);
  background-image: url(http://localhost:9080/hdwpbooks/images/button_nook2.png);
  background-size:cover;
}
.fourth_circle
{
  z-index: 1;
//  background-image: url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/173024/jonathanlarradet.png);
  background-image: url(http://localhost:9080/hdwpbooks/images/button_kobo2.png);
  background-size:cover;
}
.container_circle:hover .second_circle
{
  left:20px;
}
.container_circle:hover .third_circle
{
  right:50px;
}
.container_circle:hover .fourth_circle
{
  bottom:60px;
}