:root {
  --spider-btt-bg: #000000;
  --spider-btt-color: #ffffff;
  --spider-btt-bg-hover: #0f6cf8;
}
.spider-backtotop {
  border: 1px solid #ffffff;
  position: fixed;
  right: 20px;
  bottom: 20px;
  width: 52px;
  height: 52px;
  border-radius: 999px;
  background: var(--spider-btt-bg);
  color: var(--spider-btt-color);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.25);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.25s, transform 0.25s, background 0.2s;
  transform: translateY(8px);
  z-index: 9999;
}
.spider-backtotop svg {
  width: 26px;
  height: 26px;
}
.spider-backtotop:hover {
  background: var(--spider-btt-bg-hover);
}
.spider-backtotop.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce) {
  .spider-backtotop {
    transition: none;
  }
}