Summing up: Don't touch your computer
Spending a few hours, or even a week's analysis time can save you an immense amount if development, test, implementation and maintenance time in the future. Systems analysis for HTML and CSS implementation is as important a part of the website design process as a functional specification.
Ideally, you would want to pore over your supporting documentation, with your designs, flowcharts and wireframes posted up on your office walls and get everything sorted out on paper before commiting to a particular CSS/HTML build methodology, and then document your thought process.
The task of allocating work to your front-end development team then becomes easier and the build process more straightforward.
It's as true with the front-end as it is anywhere else: a little bit of forethought can save you days overall.
