The graphical bar that changes width to reflect the progress percentage does a fine job. The power of the progressbar widget is in the ability to see, at a glance, how much progress has been made, or how much of a resource is being utilized. But there are times when we could use some accuracy with regard to the percentage, that is, a label showing the underlying percentage.
The progressbar widget has the ability to display the label inside the progressbar container, which is more intuitive than displaying the percentage label outside of the widget. Let's look at how we can extend the theme CSS, supply additional markup to the widget, and extend the progressbar to take advantage of these new additional features in order to display the label.