/* ЗАМЕНИ rec123456789 на свой блок */
#rec2323416521{
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 9999;

  /* старт: скрыто */
  transform: translateY(-120%);
  opacity: 0;
  pointer-events: none;

  transition: transform .25s ease, opacity .25s ease;
}

/* показ */
#rec2323416521.menu-visible{
  transform: translateY(0);
  opacity: 1;
  pointer-events: auto;
}