input[type=number].otp {
    height: 45px;
    width: 45px;
    font-size: 25px;
    text-align: center;
    border: 1px solid #999;
    border-radius: 5px; 
}
input[type=number].otp::-webkit-inner-spin-button,
input[type=number].otp::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}