/* ============================================================
   Global Back to Top Button
   Used by: Homepage, Dashboard, Calculator, Products pages
   ============================================================ */

.site-back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  z-index: 9999;
  background: #059669;
  color: #fff;
  border: none;
  border-radius: 50%;
  width: 3rem;
  height: 3rem;
  cursor: pointer;
  font-size: 1.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
}

.site-back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.site-back-to-top:hover {
  background: #047857;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.35);
}

.site-back-to-top:active {
  transform: translateY(0);
}

/* Responsive: smaller on mobile */
@media (max-width: 640px) {
  .site-back-to-top {
    width: 2.5rem;
    height: 2.5rem;
    bottom: 1.5rem;
    right: 1.5rem;
    font-size: 1rem;
  }
}