/* Máy tính khoa học — responsive */

@media (max-width: 540px) {
  .mt-container { padding-top: 24px; max-width: 100%; }
  .mt-calc { padding: 12px; }
  .mt-display { padding: 10px 12px; min-height: 90px; }
  .mt-display-expr { font-size: 1.15rem; }
  .mt-display-result { font-size: 1.35rem; }
  .mt-key { padding: 12px 4px; font-size: 0.85rem; }
  .mt-key.mt-num { font-size: 1rem; }
  .mt-key.mt-op { font-size: 1.05rem; }
  .mt-key.mt-eq { font-size: 1.15rem; }
  .mt-history-row { grid-template-columns: 1fr auto; }
  .mt-history-eq { display: none; }
}