Yet CSS supports properties that plain HTML does not, such as image opacity. For example, if you want a transparent photo of your company headquarters to appear on your website homepage, you can ...

This code creates a CSS class named redBorder. If one of your HTML img tags references this class, site visitors see a solid red border around the image when viewing it on your webpage.

While HTML, CSS and JavaScript are powerful tools, they tend to run out of steam with development of advanced web applications that store data on the client side and manage complex state transitions.