.quantity {
  position: relative;
}

input[type=number]::-webkit-inner-spin-button,
input[type=number]::-webkit-outer-spin-button
{
  -webkit-appearance: none;
  margin: 0;
}

input[type=number]
{
  -moz-appearance: textfield;
}

.quantity input {
  width: 45px;
  height: 42px;
  line-height: 1.65;
  float: left;
  display: block;
  padding: 0;
  margin: 0;
  padding-left: 20px;
  border: 1px solid #eee;
}

.quantity input:focus {
  outline: 0;
}

.quantity-nav {
  float: left;
  position: relative;
  height: 42px;
}

.quantity-button {
  position: relative;
  cursor: pointer;
  border-left: 1px solid #eee;
  width: 20px;
  text-align: center;
  color: #333;
  font-size: 13px;
  font-family: "Trebuchet MS", Helvetica, sans-serif !important;
  line-height: 1.7;
  -webkit-transform: translateX(-100%);
  transform: translateX(-100%);
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  -o-user-select: none;
  user-select: none;
}

.quantity-button.quantity-up {
  position: absolute;
  height: 50%;
  top: 0;
  border-bottom: 1px solid #eee;
}

.quantity-button.quantity-down {
  position: absolute;
  bottom: -1px;
  height: 50%;
}

    jQuery('<div class="quantity-nav"><div class="quantity-button quantity-up">+</div><div class="quantity-button quantity-down">-</div></div>').insertAfter('.quantity input');
    jQuery('.quantity').each(function() {
      var spinner = jQuery(this),
        input = spinner.find('input[type="number"]'),
        btnUp = spinner.find('.quantity-up'),
        btnDown = spinner.find('.quantity-down'),
        min = input.attr('min'),
        max = input.attr('max');

      btnUp.click(function() {
        var oldValue = parseFloat(input.val());
        if (oldValue >= max) {
          var newVal = oldValue;
        } else {
          var newVal = oldValue + 1;
        }
        spinner.find("input").val(newVal);
        spinner.find("input").trigger("change");
      });

      btnDown.click(function() {
        var oldValue = parseFloat(input.val());
        if (oldValue <= min) {
          var newVal = oldValue;
        } else {
          var newVal = oldValue - 1;
        }
        spinner.find("input").val(newVal);
        spinner.find("input").trigger("change");
      });

    });