@media (max-width: 980px) {
  .app-header {
    flex-direction: column;
    align-items: stretch;
  }

  .app-nav {
    justify-content: center;
  }

  .dashboard-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .page-shell,
  .content-shell,
  .login-shell {
    padding: 1rem;
  }

  .dashboard-grid {
    grid-template-columns: 1fr;
  }

  .app-nav {
    gap: 0.5rem;
    flex-direction: column;
  }
}