It entirely depends on the questions as to how much is the Web programmer involved. Normally a designer should provide the styling docs such as CSS , other window designs that he has come up with and documents regarding how things are related to each other. But ya the view varies from person to person and also situation to situation.
What i generally do is hand over a PSD and any other graphics needed. Then, after the programmer write the html, CSS and other code I edit the CSS and tweak/correct it. However, each project varies depending on size, needs and the capabilities of the programmer.