<form action id="buy_product_form">
  <div class="modal-product">
    <div class="modal-product__image">
      <img src="{product-image}" alt="">
    </div>
    <div class="modal-product__content">
      <div class="modal-product__info">
        <span>Блок:</span>
        <span>{product-name}</span>
      </div>
      <div class="modal-product__info">
        <span>Стоимость за шт:</span>
        <span>{product-price} рублей</span>
      </div>
      <div class="modal-product__info">
        <span class="mb-1">Количество:</span>
        <div class="form-group mb-1">
          <input type="number" class="form-control" name="product_amount" id="product_amount" placeholder="Количество" required>
        </div>
      </div>
    </div>
  </div>
  <button type="button" class="cabinet-button" onclick="buy_product('{product-id}')">Купить</button>
</form>
