.btn-loading {
    pointer-events: none;
    opacity: 0.7;
}

.btn-loading::after {
    content: '';
    display: inline-block;
    width: 11px;
    height: 11px;
    margin-left: 7px;
    border: 2px solid currentColor;
    border-right-color: transparent;
    border-radius: 50%;
    animation: btn-spin 0.6s linear infinite;
    vertical-align: middle;
}

@keyframes btn-spin {
    to { transform: rotate(360deg); }
}