As someone who both codes and designs, I find it efficient to create the design in HTML and CSS.
Andrei Says...

Agreed. I would also mention that, with projects involving responsive page layouts, you don’t have to manage multiple static versions of the same design. Instead you build your design and define its behavior at different screen sizes simultaneously, testing for stress points as you go.

The initial level of effort for setting up a grid and basic pattern library in code is relatively high, but as a project grows in size and complexity the benefits become clear very quickly.