Client-side full-text search in CSS by François Zaninotto.
Not really “full-text search” in any meaningful sense of the phrase.
But I can imagine it being very useful and the comments to his post about “appropriate” use of CSS are way off base.
The only value of CSS or Javascript or (fill in your favorite technology) is creation and/or delivery of content to a user.
Despite some naming issues, this has the potential to deliver content to users.
You may have other criteria that influence you choice of mechanisms but “appropriate” should not be one of them.