Popup form in Woocommerce

Add script blow to function.php

function hdev_popup_form()
{
    if (is_singular('product')):

        ?>
        <div id="dathang" class="lightbox-by-id lightbox-content mfp-hide lightbox-white">
            <div class="row">
                <div class="col medium-6">
                    <?php the_post_thumbnail(); ?>
                    <?php woocommerce_template_single_title(); //Get TITLE ?>   
                    <?php woocommerce_template_single_price(); // Get PRICE ?> 
                    <?php woocommerce_template_single_excerpt(); // Get DESCRIPTION ?> 
                </div>
                <div class="col medium-6">
                    <?php echo do_shortcode('[contact-form-7 404 "Not Found"]'); ?>
                </div>
            </div>

        </div>

        <?php
    endif;
}
add_action('wp_footer', 'hdev_popup_form');
function hdev_popup_btn()
{ ?>
    <a href="#dathang" class="button">Yêu cầu tư vấn</a>
<?php }
add_action('woocommerce_before_add_to_cart_form', 'hdev_popup_btn');