Things to do:

• Find a way to hide style declarations from browsers that don’t support data: URLs, or find a way to test in javascript for data: url support.
• Try to actually care what my website looks like in Internet Explorer.

Well, duh. Figured that first one out rather quickly once I thought about it. Put the styles you don’t want IE &c. to see in a <link> tag, and set the href to a data: URL itself. Naturally, a browser that doesn’t support data: URLs won’t see styles imported in this way.

Still working on that second one, though.