.full-size,
.bg-full {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-position: center center;
  background-repeat: no-repeat;
  -moz-background-size: cover;
  -o-background-size: cover;
  -webkit-background-size: cover;
  background-size: cover;
  -ms-behavior: url("/background-size.min.htc");
}

.bg-parent {
  position: relative;
}
.full-size,
.bg-full {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.bg-full {
  background-position: center center;
  background-repeat: no-repeat;
  -moz-background-size: cover;
  -o-background-size: cover;
  -webkit-background-size: cover;
  background-size: cover;
  -ms-behavior: url("/background-size.min.htc");
}

.bg-parent {
  position: relative;
}
Split .bg-full from .full-size as they are not the same
Split .bg-full from .full-size as they are not the same
