off the top of my head, hide an element with css and then get :hidden elements with that id?
something like.... <html> <head> <script type="text/javascript" src="http://www.google.com/jsapi"></script> <script type="text/javascript"> google.load("jquery", "1.3.2"); google.setOnLoadCallback(function() { if ( testCSS() ) alert("CSS is enabled"); }); function testCSS() { var css = $('#test-css:hidden').length if ( css >= 1 ) return true; return false; } </script> </head> <body> <div id="test-css" style="display:none;">please enable css</div> </body> </html>