This is an example of how to use CSS with semantic data. In this case, all bird names should be in red. So wren, blue jay, and eagle are in red. If I late decide to do some other feature with the bird names, for example italize them, I can change the CSS in one place and have it change all the bird names.
You will be hard pressed to find many non-computer scientist who understand that text is not about formatting, which after all is how it has always been treated. The concept that there is semantic data in written text is obvious if you get it. The world is full of semantic information, and using it to express ideas is extremely powerful, and one of the most powerful uses of the www.