.content-loading {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    /* Cover all reader overlays, including Server-mode AI paragraph triggers. */
    z-index: 10090;
    background: var(--card-bg);
    background: color-mix(in srgb, var(--card-bg) 72%, transparent);
    -webkit-backdrop-filter: blur(12px) saturate(1.05);
    backdrop-filter: blur(12px) saturate(1.05);
}

.content-loading:not(.is-visible) { display: none; }

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 5px solid var(--border);
    border-color: color-mix(in srgb, var(--text-secondary) 24%, transparent);
    border-top-color: var(--loading-spinner, var(--button-bg));
    border-radius: 50%;
    animation: loading-spin 1s linear infinite;
}

@keyframes loading-spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

@media (prefers-reduced-motion: reduce) {
    .loading-spinner { animation: none; }
}