Firefinder is an extension to Firebug (in Firefox) and offers the functionality to, in a quick way, find HTML elements matching chosen CSS selector(s) or XPath expression. It allows you to instantly test your CSS selectors in the page while seeing the content at the same time, and matching elements will be highlighted.
Extension qui vient compléter Firebug, donne le détail de chaque propriété css ou attribut html de la page, notamment les navigateurs sur lesquels ils sont supportés.