Make it possible to style `a.accordion-toggle`-links based on whether the Bootstrap collapse/accordion item is collapsed or not. The CSS-class "active" means that a `accordion-group` is open, the lack of it means it's closed. If it wasn't for the fact that the `.collapsed` class is not added initially to a collapsed `a.accordion-toggle` element,…

active-collapsible.js

jQuery.ready(function() {
  $('.accordion').on('hide', function(e) {
    $(e.target).parent().find('.accordion-toggle').first().removeClass('active');
  }).on('show', function(e) {
    $(e.target).parent().find('.accordion-toggle').first().addClass('active');
  });
})

style.css

.accordion .accordion-toggle.active {
  font-weight: bold;
}