#ujk-back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  background: var(--ujk-dominant, #e3001b);
  color: #fff;
  border: none;
  width: 46px;
  height: 46px;
  font-size: 22px;
  cursor: pointer;
  border-radius: 0;
  opacity: 0;
  visibility: hidden;
  transition: opacity .3s ease, visibility .3s ease, transform .3s ease;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
}

#ujk-back-to-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

#ujk-back-to-top:hover {
  background: var(--ujk-dominant, #e3001b);
  filter: brightness(1.1);
}