Wikimedia Bugzilla is closed!

A lot of stuff is done to the "# references" bars on items with javascript that could be done much more efficiently with CSS. 
1. JS adds this element to the DOM: 
<span class="ui-toggler-icon ui-icon ui-icon-triangle-1-s ui-toggler-icon3dtrans"></span>
and it does nothing more than add a little arrow image to the bar. CSS ::before generated content could be used instead. (If it weren't for the little rotate animation, this would ideally use a background image.)
2. .ui-toggler is constantly listening for mouseovers so that it can add the "ui-state-hover" class to style the little arrow. Solution: Use the :hover pseudoclass.
3. JS adds all sorts of classes all over the place to style it differently than how the JS-disabled users get. Solution: Use .client-js CSS to have it styled right in the first place.
There is no reason for JS to be fiddling with this bar at all unless the user actually clicks on it.