.o-link-group__item, .js-more {
    display: none;
}

.is-active {
    display: block;
    opacity: 0;
    animation: fadeIn 0.2s forwards;
}

.js-more.is-active {
    display: inline-block;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to   { opacity: 1; }
}