.bg {
  position: fixed;
  width: 100%;
  height: 100%;
  display: block;
  left: 0;
  top: 0;
  background-repeat: no-repeat;
  background-position: center center;
  background-size: cover;
  opacity: 0.0001;
  transition: all 1s ease-out;
  z-index: -1;
}

.bg.bg-1 {
  background-image: url('../images/resale/base_01.jpg');
}

.bg.bg-2 {
  background-image: url('../images/resale/base_02.jpg');
}

.bg.bg-3 {
  background-image: url('../images/resale/base_03.jpg');
}

.bg.active {
  opacity: 1;
}