function turn_rm_toc_collapsable() {
    ?>
    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
    <script>
        jQuery(document).ready(function() {
            jQuery("div.wp-block-rank-math-toc-block").each(function() {
                var toggleButton = jQuery('<button class="toggle-button">Table of Contents [show]</button>');
                jQuery(this).find('h2').html(toggleButton);

                var nav = jQuery(this).find("nav");
                nav.css("overflow", "hidden");
                nav.css("max-height", "0");

                toggleButton.on('click', function() {
                    if (nav.css("overflow") == "hidden") {
                        nav.css("overflow", "visible");
                        nav.css("max-height", "100%");
                        toggleButton.text('Table of Contents [hide]');
                    } else {
                        nav.css("overflow", "hidden");
                        nav.css("max-height", "0");
                        toggleButton.text('Table of Contents [show]');
                    }
                });
            });
        });
    </script>
    <?php
}

add_action( 'wp_footer', 'turn_rm_toc_collapsable' );