.scroll-top {
  width: 40px;
  height: 40px;
  line-height: 40px;
  position: fixed;
  top: 100%;
  right: 50px;
  font-size: 16px;
  border-radius: 4px;
  z-index: 99;
  text-align: center;
  cursor: pointer;
  transition: 1s ease;
  border: none;
  &:after{
    position: absolute;
    z-index: -1;
    content: '';
    top: 100%;
    left: 5%;
    height: 10px;
    width: 90%;
    opacity: 1;
    background: radial-gradient(ellipse at center, rgba(0, 0, 0, 0.25) 0%, rgba(0, 0, 0, 0) 80%);
  }
  &.open{
    top: 90%;
  }
}
