On most projects I've been one, designers has produced HTML code, then developers turned it into ASP.NET, including master-pages etc that should really be a part of design.
After it has become ASP.NET, designers could not work on the code with their tools.
I know that a lot of the design of ASP.NET is made with the purpose of separating code and design, and in principle designers should be able to work on design aspects with the Visual Web Developer, but I've never seen a designer using VWD.
How is cooperation done in practice, and what is about the best one can expect from a designer?