Input number with plus/minus buttons [html,sass]

number-count-input.html

<div class="number-input">
  <button type="button" onclick="this.parentNode.querySelector('input[type=number]').stepDown()"></button>
  <input class="quantity" min="0" name="quantity" value="1" type="number">
  <button type="button" onclick="this.parentNode.querySelector('input[type=number]').stepUp()" class="plus"></button>
</div>
<style>
  .number-input {
  display: inline-flex;
  width: 80px;
  height: 30px;
  background-color: #f9f9f9;
  &, & * {
    box-sizing: border-box;
  }
  & input[type="number"] {
    -webkit-appearance: textfield;
    -moz-appearance: textfield;
    appearance: textfield;
    border: 0px;
    padding: 0;
    box-shadow: none !important;
    font-family: sans-serif;
    font-size: 14px;
    width: 30px;
    height: 100%;
    text-align: center;
    color: #777777;
    background-color: #f9f9f9;
  }

  & input[type=number]::-webkit-inner-spin-button,
  & input[type=number]::-webkit-outer-spin-button {
    -webkit-appearance: none;
  }
  & button {
    position: relative;
    outline:none;
    -webkit-appearance: none;
    background-color: transparent;
    border: none;
    align-items: center;
    justify-content: center;
    width: 30px;
    height: 100%;
    cursor: pointer;
    margin: 0;
    font-family: "Helvetica";
    font-size: 16px;
    color: #999999;
    font-weight: normal;
    position: relative;
    &:hover:after {
      background-color: #eee;
    }
    &:after {
      display: inline-flex;
      position: absolute;
      justify-content: center;
      align-items: center;
      top: 0px;
      left: 0;
      right: 0;
      width: 100%;
      height: 100%;
      bottom: 0px;
      margin: auto;
      content: '−';
    }
    &.plus:after {
      content: '+';
    }
  }
}
</style>