[pawelk]

Converting PSDs to HTML/CSS has been my job for the past ten years. The "PSD that client has already approved" is part of the problem, because what's been approved is a picture of the website which may be very close to reality under some circumstances, but not necessarily what's going to be rendered on an ancient corporate workstation with IE7 which, by coincidence, is what the client uses to test the website.

Now the workflow slowly evolves and Photoshop mock-ups are still part of it, but what the client accepts is the visual style, mood, UX, content strategy etc. The design team provides style guides, graphical assets, some key components. The UX team may provide a clickable prototype or just sketches of individual pages. Front-end devs build HTML/CSS components, then individual page templates which are usually integrated with server-side logic and filled with content. Everyone can be involved at any stage so it's not a typical waterfall process, rather combining the expertise of different professionals to deliver the best product.