A CSS coverage tool written in JavaScript.
The CSS coverage tool reports the CSS rules which are matching the DOM.
Step 1: Find a CSS parser that runs in the browser. This blog is suggesting Gonzales as the best CSS parser written in JavaScript.
Step 2: Find a CSS selector engine. JQuery should do this trick.
Step 3: Combine the CSS parser and CSS selector engine. Parse css, query these selectors and store the number of hits.
Todo: Step 4: Find a pretty print CSS engine. The sunlightjs is highlighting source code and has support for CSS.