The reason I usually use hex over rgb is because it's easier to snag the hex color from the Photoshop layout given to me. That, and if I'm not using alpha then I suppose I don't really care that much.
I never liked the double colons for pseudo selectors either. I kind of understand the idea of using two colons for the pseudo elements and single colon for pseudo classes to differentiate the two. But again, I can't seem to care that much. I can tell what they are by their names.
The correct number for !important should be zero but it's whatever number of times you have to use it because someone inlined styles into the HTML and you don't have access to remove it.
* `content` is in the top 5 properties?
* Glad to see nobody else uses two colons on pseudo selectors.
* I can't believe how rare rgb color usage is! 0.4%? hsl I can believe.
* I'd be interested to see how many sites use `!important` (the correct number in a style sheet is zero).