masterRule.js

var masterRule = function(el, recurse) {
    var rules = [];
    var rule = [];
    var nodeName, id, classes;

    do {
        nodeName = el.nodeName.toLowerCase();

        if (nodeName === 'html') { break; }

        rule.push(nodeName);

        id = el.id;
        if (id) {
            rule = rule.concat(['#', id]);
        }

        classes = el.className;
        if (classes) {
            classes = classes.split(' ');
            rule = rule.concat(['.', classes.join('.')]);
        }

        rules.unshift( rule.join('') );
        rule = [];

        el = el.parentNode;
    } while (el && recurse);

    return rules.join(' ');
};