add to cart in collection page.liquid

         {% if product.variants.size > 0 %}
          <form action="/cart/add" method="post" enctype="multipart/form-data" class="product-form product">
            <input type='hidden' name='id' value="{{product.selected_or_first_available_variant.id}}" />
            <input type='hidden' name='quantity' value="1" />
            <button type="submit" name="add"  {% unless product.available %} disabled {% endunless %} class=" {% unless product.available %} disabled {% endunless %} btn product-form__cart-submit{% if product.options.size == 1 and product.variants[0].title == 'Default Title' %} product-form__cart-submit--small{% endif %} btn-primary btn-sm  btn-lg">
              <span>
                {% if product.available %}
                {{ 'products.product.add_to_cart' | t }}
                {% else %}
                {{ 'products.product.sold_out' | t }}
                {% endif %}
              	
              </span>
            </button>

          </form>
          {% else %}
          {% if section.settings.use_quick_view %}
          {% include 'product-quick-view-btn', buttonType:"red" %} 
          {% endif %}
          {% endif %}