@media (max-width: 900px) {
  .hero-grid, .grid-3, .grid-2, .footer-grid { grid-template-columns: 1fr; }
  .main-nav {
    display: none; position: absolute; left: 1rem; right: 1rem; top: 74px;
    padding: 1rem; background: #111b2e; border: 1px solid var(--color-border);
    border-radius: 1rem; flex-direction: column; align-items: stretch;
  }
  .main-nav.is-open { display: flex; }
  .nav-toggle { display: inline-flex; background: transparent; color: white; border: 1px solid var(--color-border); padding: .55rem .8rem; border-radius: .7rem; }
  .mega-menu { position: static; width: 100%; margin-top: .75rem; grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .hero { padding: 5rem 0 4rem; }
  .section { padding: 4rem 0; }
  .stat-row, .form-grid { grid-template-columns: 1fr; }
  .field-full { grid-column: auto; }
  .footer-bottom { flex-direction: column; }
}