CSS Lost on PostBack in ASP.NET

Where oh where has my CSS gone, oh where oh where could it be??? I was recently doing some work on an older application that had been since updated to take advantage of the newer ASP.NET features an techniques. However, in a certain piece of functionality in the application the user would click a "Submit" button, a client side script would be run and then after the PostBack occurred a bunch of CSS would be lost. Read about the fix in this blog post.