#loader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255,255,255,0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    visibility: hidden;
    opacity: 0;
    transition: opacity .3s ease;
    z-index: 9999;
}

#loader.show {
    visibility: visible;
    opacity: 1;
}

.spinner {
    width: 60px;
    height: 60px;
    border: 6px solid #ddd;
    border-top-color: #3498db;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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