.req-btn-loading {
    position: relative;
    pointer-events: none;
}

.req-btn-loading:after {
    -webkit-animation: btn-loading 1s linear infinite;
    animation: req-btn-loading 1s linear infinite;
    background: repeating-linear-gradient(-60deg, rgba(255, 255, 255, 0.15), rgba(255, 255, 255, 0.15) 1em, rgba(0, 0, 0, 0.15) 1em, rgba(0, 0, 0, 0.15) 2em);
    background-size: 200%;
    content: "";
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
}

@keyframes req-btn-loading {
    from {
        background-position: -4em 0;
    }
    to {
        background-position: -1.7em 0;
    }
}