@w-back-top:~ "w-back-top";

.@{w-back-top} {
  position: fixed;
  bottom: 50px;
  right: 50px;
  cursor: pointer;
  z-index: 1006;
  transition: all 1s;
  &.no-fixed {
    cursor: auto;
    position: static;
  }
  &-hide {
    transition: all 1s;
    opacity: 0;
    height: 0px;
  }
  &-show {
    opacity: 1;
  }
}