.griglia {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
}
.griglia article { padding: 1rem; border: 1px solid #174a7e; }
@media (min-width: 48rem) {
  .griglia {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}