/* ========================================
   BOTÓN SCROLL TO TOP
======================================== */
.scroll-to-top {
  position: fixed;
  bottom: 100px;
  right: 30px;
  z-index: var(--z-fixed);

  width: 50px;
  height: 50px;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;

  transition: all var(--transition-normal);
  font-size: var(--text-xl);
  box-shadow: var(--shadow-md);

  /* Estado inicial: invisible */
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);

  &:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
  }
}

/* <button class="scroll-to-top visible"> */
.scroll-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

@media screen and (min-width: 768px) {
  .scroll-to-top {
    bottom: 120px;
  }
}