.loader-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 9999;

    /* fade effect */
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.loader-overlay.show {
    opacity: 1;
    visibility: visible;
}

.loader {
    border: 8px solid #f3f3f3;
    border-top: 8px solid #3498db;
    border-radius: 50%;
    width: 60px;
    height: 60px;

    /* rotation animation */
    animation: spin 0.5s linear infinite;
    /* fast rotation */
}

@keyframes spin {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}