function hideDupDate() {
    var _year = "", _month = "",
        $articles = $("article.list:visible");

    $articles.each(function(index, article) {
        var $year = $(article).find("time.year"),
            year = $year.text(),
            $month = $(article).find("time.month"),
            month = $month.text();
        
        if (_year !== year) {
            _year = year;
            $year.css('color', '#888');
        } else {
            $year.css('color', 'white');
        }
    
        if (_month !== month) {
            _month = month;
            $month.css('color', '#888');
        } else {
            $month.css('color', 'white');
        }
    });
}