.letter-grid.letter-level-grid {
  width: min(640px, 100%);
  grid-template-columns: repeat(var(--letter-columns, 3), minmax(0, 1fr));
  gap: clamp(7px, 1.6vw, 12px);
}

.letter-level-5 .letter-card,
.letter-level-6 .letter-card {
  border-radius: 13px;
  font-size: clamp(1.2rem, 3.4vw, 2rem);
}

@media (max-width: 760px) {
  .letter-panel { justify-content: flex-start; }
  .letter-grid.letter-level-grid { gap: 6px; }
  .letter-level-6 .letter-card { border-radius: 10px; font-size: clamp(1rem, 5vw, 1.45rem); }
}