This section isn't strictly about CSS, but does discuss a replacement for a common CSS-driven solution for adding icons to applications so this seems such as the best place to discuss it.
If you're reading this book you're probably somewhat familiar with the idea of icon fonts such as GLYPHICONS (http://glyphicons.com/) or Font Awesome (https://fontawesome.com/icons?from=io). If you're not, they are fonts that, instead of representing characters that can be read as language (as in, the characters that you're reading right now), they present different images that can be used as icons for a site or application.
For example, you could create an interface for a video player using Font Awesome without having to design ...
