您需要的只是jQuery的一点点

What you need is little bit of jquery

请参见此处

jQuery

$('#datetimepicker1').click(function(){
    var popup =$(this).offset();
    var popupTop = popup.top - 40;
    $('.ui-datepicker').css({
      'top' : popupTop
     });
});

有关日期选择器的定位，请阅读这里

About positioning of datepicker read here