Sounds like a lot of work: how's this useful?
You might now suggest that with all the effort of writing your analysis up, you may as well have written the CSS. It depends – on a small scale project, the time taken to document your CSS/HTML 'plan of action' would take longer than to write the CSS. The return on your time investment comes in the future when components are added and unordered lists appear on the page in new and exceptional circumstances: you'll be able to cater for these changes.
On a larger site, the CSS/HTML analysis helps speed up development time, as modules can be handed across to developers (as exceptions can be handled by descendent selectors) before full pages are built, and time is saved in actual CSS development as less experienced coders will be able to take on sub-sections of the site.
In terms of maintenance, you'll be able to come back to the site and understand your decisions without having to read lots of inline commenting, and without having to use developer toolbars to reverse engineer what you've built.
Dealing with exceptions
You may find that you are given a design with thematically strong styling: the typography is consistent, the styling devices, backgrounds and colours all follow a theme, but their relationship to functional modular elements (e.g. A search box, a list of associated articles) varies across pages. This is obviously poor practice from a point of view of usability (you want the user to get 'used' to using certain items and sub-consciously expecting to see certain items in the same style) but it can and will occur.
You may also find that the outline page hierarchy of headings and subheadings are styled differently on differing pages – a heading 3 may look like a heading 4 on other pages. You may at this stage want to put this to the designer, but you may well not have that opportunity. If so, the best thing is to have a rather clumsy looking long series of 'edge-case' examples in your CSS.
If, in the future, the next design needs to change all these elements' colour, say, they will all be in one place. If, in the future, they are all standardised by their place in the outline page hierarchy, then you only need to comment out in one place.
Next - CSS Kung-fu, or, Techniques for CSS/HTML Systems Analysed Site Designs
