Pure JavaScript function to find a CSS rule by it's selector string

searchrule.js

function findCssRule(selectorString) {
    // helper function searches through the document stylesheets looking for @selectorString
    // will also recurse through sub-rules (such as rules inside media queries)
    function recurse(node, selectorString) {
        if (node.cssRules) {
            for (var i = 0; i < node.cssRules.length; i++) {
                if (node.cssRules[i].selectorText == selectorString) {
                    return node.cssRules[i].style;
                }
                if (node.cssRules[i].cssRules) {
                    var found = recurse(node.cssRules[i], selectorString);
                    if (found) return found;
                }
            }
        }
        
        return false;
    }
    
    for (var i = 0; i < document.styleSheets.length; i++) {
        var sheet = document.styleSheets[i];
        if (sheet.cssRules) {
            var found = recurse(sheet,selectorString);
            if (found) return found;
        }
    }
    
    return false;
}