.btn-loading {
    position: relative;
    color: rgba(255,255,255,.4) !important;
    pointer-events: none
}

.btn-loading:before {
    content: "";
    box-sizing: border-box;
    position: absolute;
    top: 50%;
    left: 50%;
    width: 2rem;
    height: 2rem;
    margin-top: -1rem;
    margin-left: -1rem;
    border-radius: 50%;
    border: 2px solid #eee;
    border-top-color: #00aeef;
    animation: spinner .6s linear infinite
}

@keyframes spinner {
    to {
        transform: rotate(360deg);
    }
}