.scrolltop {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  position: fixed;
  width: 42px;
  height: 42px;
  right: 50px;
  bottom: 25px;
  margin: 0;
  z-index: 10000;
  opacity: 0;
  visibility: hidden;
  text-align: center;
  line-height: 44px;
  color: #fff;
  background: #662d91;
  cursor: pointer;
  -webkit-border-radius: 50%;
  -moz-border-radius: 50%;
  border-radius: 50%;
  border: 1px solid #662d91;
}
.scrolltop.on {
  opacity: 0.6;
  visibility: visible;
  -webkit-transition: opacity .3s ease;
  transition: opacity .3s ease;
}
.scrolltop.on:hover {
  opacity: 1;
}
.scrolltop .fa {
  line-height: 38px;
}