function tnc_support_modify_a_tags() {
    ?>
    <script type="text/javascript">
        document.addEventListener('DOMContentLoaded', function() {
            function tnc_support_update_links() {
                // Find all 'a' tags with the class 'fullscreen-mode'
                const fullscreenLinks = document.querySelectorAll('a.fullscreen-mode');
                
                // Loop through the NodeList and update the target to '_parent'
                fullscreenLinks.forEach(function(link) {
                    link.setAttribute('target', '_parent');
                });
            }

            // Call the function to update the links
            tnc_support_update_links();
        });
    </script>
    <?php
}

// Hook it to the WordPress footer or wp_enqueue_scripts action
add_action('wp_footer', 'tnc_support_modify_a_tags');