.back-to-top {
  width: 40px;
  height: 40px;
  background-color: var(--back-arrow);
  border-radius: 50%;
  /* 4px; */
  /*  */
  position: fixed;
  right: 15px;
  bottom: 70px;
  /*  */
  z-index: 996;
  transition: all 0.4s;
  /*  */
  display: grid;
  place-items: center;
  /*  */
  visibility: hidden;
  opacity: 0;
}

.back-to-top:hover {
  background-color: var(--back-arrow-hover);
}

.back-to-top.active {
  visibility: visible;
  opacity: 1;
}

/* - - - - - - - - - - - - - - -  */
.arrow-up {
  margin-top: 5px;
  padding: 5px;
  /*  */
  border: solid var(--border-arrow);
  border-width: 0 5px 5px 0;
  transform: rotate(-135deg);
}