button#back-to-top {
  position: fixed;
  right: 4px;
  bottom: 60px;
  opacity: 0;
  z-index: 500;
  transform-origin: 50% 49%;
  transform: translate3d(0, 0, 0) rotate(90deg);
  transition: opacity .5s;
  pointer-events: none;
}

@media (max-width: 768px) {
  button#back-to-top {
    right: -17px;
    bottom: 53px;
  }
}

button#back-to-top.on {
  opacity: 1;
  pointer-events: auto;
}

button#back-to-top span {
  position: relative;
  display: inline-block;
  vertical-align: middle;
  font-weight: 400;
  font-style: italic;
  color: #1b745e;
  font-size: 17px;
  word-spacing: 6px;
}

button#back-to-top span::before {
  content: '';
  width: 64px;
  height: 1px;
  background-color: #1b745e;
  position: absolute;
  top: 10px;
  left: -95%;
}

button#back-to-top:hover span::before {
  animation: qodef-animate-btt 1s forwards;
}

@keyframes qodef-animate-btt {
  0% {
    transform: scaleX(1);
    transform-origin: left;
  }

  30% {
    transform: scaleX(0);
    transform-origin: left;
  }

  35% {
    transform: scaleX(0);
    transform-origin: right;
  }

  100% {
    transform: scaleX(1);
    transform-origin: right;
  }
}