#loader {
    border: 5px solid #f3f3f3;
    border-radius: 50%;
    border-top: 5px solid #4f46e5;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 20px auto;
    display: none;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}
.chart-container {
    position: absolute;
    left: -9999px;
    top: -9999px;
}