Build a PHP Switcher
http://www.alistapart.com/stories/phpswitch/

Clark, Chris
List Apart, A
2002

Abstract:

ALA's open source style sheet switchers are swell so long as your visitors use compliant browsers and have JavaScript turned on. But what if they don’t? New ALA author Chris Clark tells how to build a cross-browser, backward-compatible, forward-compatible, standards-compliant style sheet switcher in just five lines of code.