First of all I think you need to think of which group to split CSS.
On 3 logical, but I don't know how it will be then easy to read:
CSS in fact is in fact just a selector+property+value
- create means top 30 selectors
- then top properties
- and top values
(after all, there's no sense in frequently used the crib to add something exotic at all from the language of CSS, or to decide whether the contrary is to add less known selectors, properties or values (because known so long known))
It is also possible for other groups to divide, intuitive and visual "character" of ordinary perception, for example:
- background
- border
- font
- field
- ...
Or to think of what other group you can divide it but the visual component or the fundamental
PS with HTML there is not so simple, I decided to see what the HTML API and realized that it was not for one day