.btn-auth {
    color: #000;
    font-size: 1.5rem;
    font-weight: 300;
    text-transform: uppercase;
    letter-spacing: 1px;
    background-color: transparent;
    padding: 10px 15px;
    display: inline-block;
    border: 0;
    border-bottom: 2px solid transparent;
    transition: border-color .3s;
    position: relative;
    top: 50%;
    -webkit-transform: translateY(-50%);
    -moz-transform: translateY(-50%);
    -ms-transform: translateY(-50%);
    -o-transform: translateY(-50%);
    transform: translateY(-50%);
    float: right;
}

.btn-auth:hover {
    color: #000;
    border-color: #000;
}