.otp-input {
  width: 3rem;
  height: 3rem;
  text-align: center;
  font-size: 1.5rem;
  font-weight: 700;
  color: #000;
  background-color: #f9fafb;
  border: 1px solid #d1d5db;
  border-radius: 0.5rem;
  outline: none;
  transition: all 0.2s ease-in-out;
}

.otp-input:focus {
  background-color: #fff;
  border-color: #166534; /* dark green */
  box-shadow: 0 0 0 2px rgba(22, 101, 52, 0.2);
}