.btn[disabled] {
    opacity: 0.65;
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

.btn.is-loading {
    position: relative;
}

.btn.is-loading::after {
    content: '';
    width: 14px;
    height: 14px;
    border: 2px solid rgba(255, 255, 255, 0.6);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    display: inline-block;
    margin-left: 6px;
}

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