.back-to-top {
  position: fixed;
  bottom: 28px;
  right: 28px;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: #2DAF83;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 6px 22px rgba(45, 175, 131, 0.45);
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity 0.28s ease, transform 0.28s ease, background 0.2s ease;
  z-index: 9998;
}
.back-to-top.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.back-to-top:hover {
  background: #1B8F6A;
  box-shadow: 0 8px 30px rgba(45, 175, 131, 0.55);
}
.back-to-top::before {
  content: '';
  display: block;
  width: 12px;
  height: 12px;
  border-left: 2.5px solid #FFFFFF;
  border-top: 2.5px solid #FFFFFF;
  transform: rotate(45deg) translate(2px, 2px);
  margin-top: 2px;
}
@media (max-width: 600px) {
  .back-to-top {
    width: 42px;
    height: 42px;
    bottom: 20px;
    right: 20px;
  }
}