.gradient-header {
  background: linear-gradient(135deg, #0f172a 0%, #064e3b 100%);
}

.card-shadow {
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.01);
}

.letter-button.active {
  background: #047857;
  color: white;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12);
}