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

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

.shopify-buy__option-select-wrapper {
  border: 1px solid var(--color-border);
  border-radius: 3px;
  box-sizing: border-box;
  position: relative;
  background: var(--color-white);
  overflow: hidden;
  vertical-align: bottom;
}

.shopify-buy__select-icon {
  cursor: pointer;
  display: block;
  fill: #798c9c;
  position: absolute;
  right: 10px;
  top: 50%;
  margin-top: -6px;
  pointer-events: none;
  width: 12px;
  height: 12px;
  vertical-align: middle;
}

.shopify-buy__option-select {
  & + .shopify-buy__option-select {
    margin-top: calc(var(--gutter) / 2);
  }
}

.shopify-buy__option-select__label {
  display: block;
  font-size: 14px;
  margin-top: 15px;
  margin-bottom: 5px;
}

.shopify-buy__btn--parent {
  & .shopify-buy__option-select__label {
    cursor: pointer;
  }
}

.shopify-buy__option-select__select {
  font-size: inherit;
  padding: 7px 10px;
  padding-right: 32px;
  border: 0;
  width: 100%;
  background: transparent;
  -webkit-appearance: none;
  -moz-appearance: none;

  &::-ms-expand {
    display: none;
  }
}

.shopify-buy__btn--parent {
  & .shopify-buy__option-select__select {
    cursor: pointer;
  }
}