a.back-to-top {
  display: none;
  width: 60px;
  height: 60px;
  text-indent: -9999px;
  position: fixed;
  z-index: 999;
  right: 20px;
  bottom: 20px;
  background: rgba(39, 174, 97, 0.5) url("/images/up-arrow.png") no-repeat center 43%;
  -webkit-border-radius: 30px;
  -moz-border-radius: 30px;
  border-radius: 30px;
  transition: all 0.2s ease-in-out 0s;
  outline: 0; }
  
  a:hover.back-to-top {
  background-color: rgba(39, 174, 97, 1);
}