Although most of the browser have developer tools in build for checking out web pages styles while developing websites. The web developer extension for Google Chrome is a very easy to use developer extension and brings in lot of features for web development. Although Chrome has its own developer tools, this extension is much more easily accessible and allows you to see the page changes right from the browser when you disable or enable any CSS elements.
The tools are neatly arranged in tabs and if you want to enable or disable any option, just need to click it.
What makes this extension useful is the ease with which it works. The live preview on website is also not blocked because of the tiny size of extension window.