document.querySelectorAll('.tocify-header .level-1 a').forEach(link => {
            link.addEventListener('click', function(e) {
                e.preventDefault();
                const parentLi = this.closest('li');
                const nextUl = parentLi.nextElementSibling;
                if (nextUl && nextUl.tagName === 'UL') {
                    nextUl.classList.contains('visible') ? nextUl.classList.remove('visible') : nextUl
                        .classList.add('visible');
                }
            });
        });