#button-to-top {
  display: inline-block;
  background-color: var(--primary-color);
  width: 50px;
  height: 50px;
  text-align: center;
  border-radius: 4px;
  position: fixed;
  bottom: 60px;
  right: 30px;
  transition: background-color .3s, 
    opacity .5s, visibility .5s;
  opacity: 0;
  visibility: hidden;
  z-index: 1000;
}
#button-to-top::after {
  /* content: "🠕"; */
  content: "";
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' style='fill: white;transform: ;msFilter:;'%3E%3Cpath d='M11 8.414V18h2V8.414l4.293 4.293 1.414-1.414L12 4.586l-6.707 6.707 1.414 1.414z'%3E%3C/path%3E%3C/svg%3E");
  /* font-weight: normal;
  font-style: normal;
  font-size: 2em;
  line-height: 50px;
  color: #fff; */
  position: absolute;
  -webkit-background-size: contain;
  background-size: cover;
  background-position: center center;
  background-repeat: no-repeat;
  width: 50px;
  height: 50px;
  top: 0;
  right: 0;
}
#button-to-top:hover {
  cursor: pointer;
  background-color: #333;
}
#button-to-top:active {
  background-color: #555;
}
#button-to-top.show {
  opacity: 1;
  visibility: visible;
}