/* --- Botón Volver Arriba (Back to Top) --- */

.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  outline: none;
  z-index: 9999;
  background: rgba(20, 25, 35, 0.6);
  backdrop-filter: blur(15px);
  -webkit-backdrop-filter: blur(15px);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-top-color: rgba(255, 255, 255, 0.35);
  border-left-color: rgba(255, 255, 255, 0.25);
  color: #ffffff;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5), 0 0 15px rgba(74, 144, 226, 0.15), inset 0 0 15px rgba(255, 255, 255, 0.03);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px) scale(0.8);
  transition: all 0.4s cubic-bezier(0.25, 1, 0.5, 1);
}

/* Estado visible (cuando se hace scroll) */

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

/* --- Efecto Hover --- */

.back-to-top:hover {
  background: rgba(148,235,37,0.3);
  border-color: rgba(120, 170, 255, 0.6);
  color: #ffffff;
  transform: translateY(-5px) scale(1.08);
  box-shadow: 0 15px 35px rgba(0, 0, 0, 0.6), 0 0 25px rgba(186,226,74,0.36), inset 0 0 20px rgba(255, 255, 255, 0.1);
}

/* --- Efecto Press (Active) --- */

.back-to-top:active {
  transform: translateY(-1px) scale(0.95);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.5), 0 0 15px rgba(74, 144, 226, 0.3), inset 0 3px 10px rgba(0, 0, 0, 0.3);
}

/* Animación del icono de flecha al hacer hover */

.back-to-top svg {
  transition: transform 0.3s ease;
}

.back-to-top:hover svg {
  transform: translateY(-2px);
}

/* --- Responsive --- */

@media (max-width: 576px) {
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 48px;
    height: 48px;
  }
}

@media (max-width: 576px) {
  .back-to-top svg {
    width: 18px;
    height: 18px;
  }
}