.navbar-nav .nav-item .dropdown-menu {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 3s, transform 5s;
  pointer-events: none;
  visibility: hidden;
}
.navbar-nav .nav-item .dropdown-menu.show {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
  visibility: visible;
}