Dropdown menu CSS

/*-- Dropdown navbar --*/
.navpregen{
  display: none;
}

.mrd-dropdown-nav{
  position: sticky;
  top: 0;
  left: 0;
  padding: 1rem;
  width: 100vw;
  text-align: center;
}
ul.menu-out, ul.menu-in{
  margin: 0;
  padding: 0;
  list-style: none;
}
ul.menu-out{
  display: flex;
  justify-content: center;
  align-items: center;
}
ul.menu-out li{
  padding:0 15px;
}
.mrd-dropdown-nav ul.menu-in{
  position:absolute;
  opacity:0;
  visibility:hidden;
  transition: all .5s;
}

.mrd-dropdown-nav li:hover ul.menu-in{
  opacity: 1;
  visibility: visible;
}