.congratulation {
    position: fixed;
    z-index: 10;
    width: 100%;
    height: 100%;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    display: none;
    background-color: rgba(255,255,255);
}
.congratulation.show {
    display: flex;
}

    .groups-link {
        background-color: rgba(255,209,98);
        padding: 3px 10px;
        margin-top: 15px;
        opacity: .3;
        transition: box-shadow .5s, opacity .5s;
        display: block;
        color: inherit;
        text-decoration: none;
    }
    .groups-link:hover {
        cursor: pointer;
        opacity: 1;
        box-shadow: 0 0 15px rgba(10,10,10,.1);
    }
    
.fade-in {
    animation: 1000ms ease 0s normal none 1 running fade-in;
}    
    
@keyframes fade-in {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}