/* Add this to your wwwroot/css/site.css or any other global CSS file */
.processing-indicator {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(255, 255, 255, 0.7);
    z-index: 1000;
    font-size: large;
    font-weight: bold;
}