.dropdown-menu {
    position: absolute;
    z-index: 1;
    opacity: 0;
    visibility: hidden;
    transition: visibility 0.5s;
    display: inline;
}

.dropdown-toggle:focus {
    pointer-events: none;
}

.dropdown-toggle:focus + .dropdown-menu {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transition: visibility 0.5s;
}