.drop-zone {
    transition: all 0.3s ease;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    background-size: 200% 200%;
    animation: gradient 3s ease infinite;
}
@keyframes gradient {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}
.drop-zone.drag-over {
    transform: scale(1.02);
}
.loading-spinner {
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top: 3px solid #60a5fa;
    width: 24px;
    height: 24px;
    animation: spin 1s linear infinite;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}