for hide all except media box..
go here:

[url]http://theftalk.com/t35465-Mere-MediaBox-%28MMb%29-2.1.html[/url]
for more info...
bout css extension...
css extension is ur css file...
try to go here: [url=http://theftalk.com/t36435-Frequently-Asked-Questions-%2AUpdated.html][b]FAQS[/b][/url]