You code the alternate style sheet by adding an extra LINK tag in the head of the document designated "alternate style sheet". Theere's apparently a w3c standard that says browsers ought include support for alternate styles. In Firefox, just click View > Page Style, and you can select one there too. Warning: If you select "no style", this page is scary.
No Style -- I see, I think. It just displays your page without looking at the style sheets, and it doesn't appear to like server-side includes either, although some Javascript seems to work.
("Feature" is quoted because we often fix bugs simply by documenting them. Another name for a documented bug is "feature.")
:-)