User Agent: Mozilla/5.0 (Windows NT 6.2; Win64; x64; rv:22.0) Gecko/20130328 Firefox/22.0 Build ID: 20130328031013 Steps to reproduce: Using the native CSS inspector in the last button of this page ( http://www.webtutorialplus.com/demo/css-buttons-hover-effect/index.html ), I tried to learn how the border was done. Actual results: Because I was only using the native inspector, I tried some of the pseudo classes, but nothing worked. Only when I sent it to a friend who used Firebug and found out it was just a :before. Expected results: Pseudo classes like before and probably after, and maybe others are not appearing in the CSS list. A printscreen of how it appears with Firebug and Inspector.