This is a colourful way to style up your lists. In this tutorial on Tuts+, you can learn how to use CSS counters to style an ordered list. CSS counters are commonly used in the sidebars on online newspapers to show a list of news articles.
If you are having trouble with the pen, try the archived copy on GitHub
See the Pen Styling CSS Counters by Envato Tuts+ (@tutsplus) on CodePen.0