.precheck-download.loading {
    pointer-events: none;
    opacity: 0.75;
}

.precheck-download .btn-spinner {
    width: 14px;
    height: 14px;
    border: 2px solid rgba(255,255,255,.4);
    border-top-color: #fff;
    border-radius: 50%;
    display: inline-block;
    vertical-align: middle;
    margin-left: 8px;
    animation: spin 0.8s linear infinite;
}

.precheck-download.loading .btn-label {
    opacity: 0.85;
}

.precheck-download.loading .btn-spinner {
    display: inline-block;
}

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