.back-to-top-btn {
  box-sizing: border-box;
  position: fixed;
  right: 30px;
  bottom: 100px;
  width: 48px !important;
  height: 48px !important;
  margin: 0;
  padding: 0 !important;
  border-radius: 50% !important;
  background: #e30613 !important;
  color: #fff;
  border: none !important;
  appearance: none;
  -webkit-appearance: none;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.25);
  z-index: 999998;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s ease, background 0.2s ease;
}
.back-to-top-btn span {
  display: block;
  transform: translateY(-1px);
}
.back-to-top-btn.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.back-to-top-btn:hover {
  background: #c40510 !important;
}
@media (max-width: 767px) {
  .back-to-top-btn {
    right: 16px;
    bottom: 90px;
    width: 42px !important;
    height: 42px !important;
    font-size: 18px;
  }
}