(function(document) {

var toggle = document.querySelector('.sidebar-toggle');
var sidebar = document.querySelector('#sidebar');
var checkbox = document.querySelector('#sidebar-checkbox');

document.addEventListener('click', function(e) {
  var target = e.target;

  if(!checkbox.checked ||
     sidebar.contains(target) ||
     (target === checkbox || target === toggle)) return;

  checkbox.checked = false;
}, false);

})(document);