main {
  max-width: 480px;
  margin: auto;
}

/* Chrome, Safari, Edge, Opera */
input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

/* Firefox */
input[type='number'] {
  -moz-appearance: textfield;
}

.btn {
  margin: auto 5px;
}

.ans {
  margin: 30px auto;
  font-size: 20px;
}

/* label focus color */
#number[type='number']:focus + label,
#baseInput[type='number']:focus + label {
  color: #1976d2;
}

/* label underline focus color */
#number[type='number']:focus,
#baseInput[type='number']:focus {
  border-bottom: 1px solid #1976d2;
  box-shadow: 0 1px 0 0 #1976d2;
}

/* radio button */
#baseE:checked + span:before,
#customBase:checked + span:before {
  border-color: #1976d2;
}

#baseE:checked + span:after,
#customBase:checked + span:after {
  background-color: #1976d2;
  border-color: #1976d2;
}