화면 가운데

HTML

<div class="className">THISHALL.COM</div>

JQUERY

<script type="text/javascript">
$( document ).ready(function() {
  $(window).resize();
}); 

$(window).resize(function(){
    $('.className').css({position:'absolute'}).css({
        left: ($(window).width() - $('.className').outerWidth())/2,
        top: ($(window).height() - $('.className').outerHeight())/2
    });
});
</script>

클릭한 위치에 레이어 띄우기

http://study.zziraweb.com/jquery/offset-%EC%9D%B4%EC%9A%A9%ED%95%98%EC%97%AC-%ED%81%B4%EB%A6%AD%ED%95%9C-%EC%9C%84%EC%B9%98%EC%97%90-%EB%A0%88%EC%9D%B4%EC%96%B4%EB%9D%84%EC%9A%B0%EA%B8%B0/