a {
    text-decoration-color: #0d6efd;
    text-decoration-thickness: 1px;
    color: #212529;
}

@keyframes flashfade {
    25% {
        background-color: #fff3cd;
        opacity: 100%;
    }

    75% {
        opacity: 75%;
    }
    
    100% {
        background-color: inherit;
    }
}

.mark_ref {
    animation: 2s flashfade;
}

#ref_list li span {
    border-radius: 2px;
}