#bigCont{
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  width: 1000px;
  height: 600px;
 
}
#cont{
position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
}
#cont div{
  position: relative;
}