(function() {
'use strict';
var sidebar = document.querySelector('.book-summary');
if (!sidebar) return;
sidebar.addEventListener('click', function(e) {
var link = e.target.closest('a');
var titleSpan = e.target.closest('.chapter-title');
var chapter = e.target.closest('.chapter.expandable');
if (!chapter) return;
var articles = chapter.querySelector('.articles');
if (!articles) return;
if (titleSpan && !link) {
e.preventDefault();
e.stopImmediatePropagation();
chapter.classList.toggle('expanded');
return;
}
if (link) {
var rect = link.getBoundingClientRect();
var clickX = e.clientX - rect.left;
if (clickX < 25) {
e.preventDefault();
e.stopImmediatePropagation();
chapter.classList.toggle('expanded');
}
}
});
})();