getElementCssStyleRules is a function to return an array of the css rules that affect the element supplied to the function...

getElementCssStyleRules.js

var getElementCSSStyleRules = function (f) {
    var myElement = f;
    var r = [];
    [].slice.call(document.styleSheets).forEach(function (rules) {
        [].slice.call(rules.rules).forEach(function (e) {
            if ([].slice.call(document.querySelectorAll(e.selectorText)).indexOf(f) !== -1) {
                e.toString = function(){return this.selectorText;};
                r.push(e);

            }
        });
    });
    return r;
};