.scroll-top-btn {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  width: 2.5rem;
  height: 2.5rem;
  border: none;
  border-radius: 999px;
  background: #10b981;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
  cursor: pointer;
  z-index: 1000;
  opacity: 0;
  transform: translateY(14px);
  pointer-events: none;
  transition: background-color 0.2s ease, transform 0.2s ease, opacity 0.2s ease, box-shadow 0.2s ease;
}

.scroll-top-btn.is-visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.scroll-top-btn:hover,
.scroll-top-btn:focus-visible {
  background: #059669;
  transform: translateY(-2px);
  box-shadow: 0 14px 28px rgba(0, 0, 0, 0.22);
}

.scroll-top-btn:focus-visible {
  outline: 2px solid #3b82f6;
  outline-offset: 3px;
}

.scroll-top-btn .material-icons {
  font-size: 1.3rem;
}

@media (max-width: 640px) {
  .scroll-top-btn {
    bottom: 1rem;
    right: 1rem;
  }
}