Are there any indicators that can reliably indicate usage of a CSS preprocessor? If so, what preprocessors are used and which ones? (Could property ordering, presence of hacks/comments, misspellings, prefixes, or source mapping comment be used to identify?)
What are the common values in ::before and ::after pseudo-element content properties?
If you leave out the identifiable CSS libraries, how does that affect the numbers? Do they scale by 10% or do the libraries (Bootstrap primarily) use rules/properties disproportionately enough to scale the other results?
What percent of files are minimized?
What does the histogram of selectors per site look like?
Edit: Also, how frequently do dataURIs show up (probably as background images)?