#backdrop {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, .35);
    z-index: 9999;
    pointer-events: all;
    /* bloquea clicks al fondo */
}

.spinner {
    width: 44px;
    height: 44px;
    border: 4px solid #fff;
    border-right-color: transparent;
    border-radius: 50%;
    animation: spin .8s linear infinite;
}

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