.back-to-top {
  position: fixed;
  left: 1.1rem;
  bottom: 1.1rem;
  z-index: 1100;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 58px;
  height: 58px;
  border-radius: 999px;
  border: 1px solid rgba(159, 255, 233, 0.72);
  background: linear-gradient(135deg, #1fd6a5, #379984);
  color: rgb(0 0 0);
  font-size: 1.35rem;
  font-weight: 700;
  text-decoration: none;
  box-shadow: 0 0 28px rgb(0 0 0), inset 0 0 18px #000000;
  transition: transform 0.3s ease, box-shadow 0.3s ease, filter 0.3s ease;
}

.back-to-top.is-hidden {
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px) scale(0.96);
  pointer-events: none;
}

.back-to-top:hover {
  transform: translateY(-4px) scale(1.04);
  filter: brightness(1.04);
  box-shadow:
    0 0 42px rgba(55, 153, 132, 0.9),
    0 0 80px rgba(55, 153, 132, 0.45);
}

.back-to-top:focus-visible {
  outline: 2px solid rgba(210, 255, 245, 0.95);
  outline-offset: 2px;
}

@media (max-width: 768px) {
  .back-to-top {
    left: 0.75rem;
    bottom: 0.75rem;
    width: 52px;
    height: 52px;
    font-size: 1.2rem;
  }
}