@nguyenmv2/buy-button/src/styles/embeds/sass/components/quantity.css

BuyButton.js allows merchants to build Shopify interfaces into any website

.shopify-buy__quantity-decrement,
.shopify-buy__quantity-increment {
  color: var(--color-title);
  display: block;
  height: 30px;
  float: left;
  line-height: 16px;
  font-family: monospace;
  width: 26px;
  padding: 0;
  border: none;
  background: transparent;
  box-shadow: none;
  cursor: pointer;
  font-size: 18px;
  text-align: center;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  border: 1px solid var(--color-quantity-border);
  position: relative;

  & svg {
    width: 14px;
    height: 14px;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-top: -6px;
    margin-left: -7px;
    fill: currentColor;
  }
}

.shopify-buy__quantity-decrement {
  border-radius: var(--border-radius) 0 0 var(--border-radius);
}

.shopify-buy__quantity-increment {
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
}

.shopify-buy__quantity {
  color: black;
  width: 45px;
  height: 30px;
  font-size: 16px;
  border: none;
  text-align: center;
  -webkit-appearance: none;
  -moz-appearance: textfield;
  display: inline-block;
  padding: 0;
  border-radius: 0;
  border-top: 1px solid var(--color-quantity-border);
  border-bottom: 1px solid var(--color-quantity-border);
}

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

.shopify-buy__quantity-container.shopify-buy__quantity-with-btns {
  overflow: hidden;

  & .shopify-buy__quantity {
    border-left: 0;
    border-right: 0;
    float: left;
  }
}