jquery.nice-number.css

.nice-number {
  display: inline-flex;
  justify-content: stretch;
}

.nice-number input {
  vertical-align: middle;
  -moz-appearance: textfield;
  box-sizing: content-box;
  margin: 0;
  text-align: center;
}

.nice-number input::-webkit-inner-spin-button,
.nice-number input::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}