.btn-loading {
    pointer-events: none;
    opacity: 0.7;
    position: relative;
    color: transparent !important;
}
.btn-loading::after {
    content: "";
    position: absolute;
    width: 16px;
    height: 16px;
    top: 50%;
    left: 50%;
    margin: -8px 0 0 -8px;
    border: 2px solid #fff;
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }