@media (max-width: 820px) {
  .shell { grid-template-columns: minmax(0, 1fr); width: 100%; overflow: hidden; }
  .sidebar, .stage { min-width: 0; width: 100%; }
  .sidebar { overflow: hidden; }
  .sidebar nav { max-width: 100%; overflow-x: auto; }
  .brand { max-width: 100%; }
  .nav-item { min-width: max-content; }
  .metrics { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .secondary-column { grid-template-columns: 1fr; }
  .unit-context { overflow-x: auto; }
}