.sub-menu-parent { position: relative; }


.sub-menu { 
  visibility: hidden; /* hides sub-menu */
  opacity: 0;
  position: absolute;
  top: 100%;
  left: 0;
  width: 100%;
  transform: translateY(-2em);
  z-index: -1;
  transition: all 0.3s ease-in-out 0s, visibility 0s linear 0.3s, z-index 0s linear 0.01s;
  background: #fff;
  border-radius: 20px;
  padding-top: 5px;
  filter: drop-shadow(0px 0px 5px #55555585);
}


.sub-menu-parent:focus .sub-menu,
.sub-menu-parent:focus-within .sub-menu,
.sub-menu-parent:hover .sub-menu {
  visibility: visible; /* shows sub-menu */
  opacity: 1;
  z-index: 1;
  transform: translateY(0%);
  transition-delay: 0s, 0s, 0.3s; /* this removes the transition delay so the menu will be visible while the other styles transition */
}