[murz]

I'm a designer who knows how to code (or more accurately: a coder who knows how to design).

When I am mocking and laying things out, it's much faster to use Photoshop because it's easier to just drag objects around instead of tweaking CSS properties (at this point I'm mostly just dragging around and resizing vectors/shapes/photos/text to get them in the right size/position).

After I'm pretty satisfied with the layout I will go into vim or Sublime Text and start hammering out the actual design in CSS. I find tweaking CSS properties and refreshing my browser to be at least as productive as editing layer styles in Photoshop (if not more productive). Features of CSS like gradients, borders, opacity, shadows, etc. actually make it a very reasonable environment for quickly iterating on designs (especially when paired with SASS/Compass or LESS). Plus it saves you a step (it's gonna need to be coded sometime anyway...). YMMV