It also supports the Firebug plug-in for Mozilla Firefox. It implements the Firebug Crossfire Debugger protocol, as well as the WebKit remote debugging protocol. There is a HTML and CSS inspector like Firebug. As Firefox 57 no longer supports XUL add-ons, Firebug is no longer compatible. Firebug and Async CSS are such add-ons. The Firebug command line accepts commands written in JavaScript. The Firebug layout tab is used to display and manipulate CSS property values. Later versions of Firebug allow users to see live changes to the CSS. All editors in Firebug support autocomplete. Combs had purchased the Firebug costume and armor from Rigger. The classes are&colon; Runner, Detonator, Rocketman, Firebug, Constructor, Rifleman, Healer, Overweight, and Infiltrator. Since Firebug is open source, users can contribute their own extensions to the Firebug community. A new Firebug debuted in Gotham Central #3. Many extensions have been made to enhance Firebug. Firebug requires a user to refresh a web page in the event of a crash.