$(function() {
    var body = $('#container'),
        bodyHeight = body.height();

    $(window).resize(function() {
        var height = ($(this).height() - bodyHeight) / 2;
        body.css('margin-top', Math.max(20, height));
    }).trigger('resize');

    $('.capcha img').click(function() {
        $(this).attr('src', this.src.split('?')[0] + '?' + new Date())
    })

});