@media (max-width: 768px) {
  .app-bar {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
  .app-main {
    grid-template-columns: 1fr;
  }
  .sidebar,
  .documents-panel,
  .detail-panel,
  .tags-panel,
  .correspondents-panel {
    min-height: auto;
  }
}