.scroll-to-top{
  position: fixed;
  bottom: 15px;
  right: 15px;
  z-index: 999;
  display: none;
}
.scroll-to-top a {
  background-color: #666;
  color: #FFF;
  padding: 10px;
}
.scroll-to-top a:hover{
  color: red;
}