@media (max-width: 768px) {
    .result-card-grid { grid-template-columns: 1fr 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
    .nav-menu { display: none; }
    .mobile-menu-toggle { display: block; }
}
@media (max-width: 480px) {
    .result-card-grid { grid-template-columns: 1fr; }
    .primary-result { font-size: 2rem; }
    .calculator-container { padding: 1rem; }
}