.cool-link {
    display: inline-block;
    color: #00134d;
    text-decoration: none;
}



.cool-link::after {
    content: '';
    display: block;
    width: 20%;
    height: 2px;
    background: #04becd;
    transition: width .3s;
}

.cool-link:hover::after {
    width: 100%;
    color: #04becd;
    //transition: width .3s;
}