First, I'm calling this a "CSS Zen Flowerpot" and not a "CSS Zen Garden" because I want to emphasize the modest scale of this assignment. A full-fledged garden is something not everyone can do because it requires space and resources, and to make a large and impressive garden takes experience and expertise. On the other hand, a flowerpot is the sort of thing that almost anyone can keep almost anyplace-- a dorm room, an apartment porch, a shelf, even a windowless school office.
Second, to extend my metaphor further, different CSS gardners will come up with different CSS flowerpots. Some of you will have cascading style sheets that are like exotic and delicate plants from far away places; some of you will have casscading style sheets that are like common and hard-to-kill plants. That's okay; both kinds of plants/style sheets have a place.
Third, the goal is to use CSS to effect the design of information (in this case, just this particular piece of information) to reach different audiences for different purposes. As Molly Holzschlag writes in her book Spring Into HTML and CSS:
Keeping presentation separate from the document means you can style that document for numerous media, including the screen, print, projection, and even handheld devices.