overlay popup with height breakpoint

checkHeight.js

var breakpoint_1 = 800;
function checkHeight(){
	var wh = $(window).height() || window.innerHeight || root.clientHeight || body.clientHeight ;
	if (wh<=breakpoint_1){
		$('html').addClass('smallscreen');
	}else{
		$('html').removeClass('smallscreen');
	};
	$('.popup').css('margin-left', $('.popup').width() / -2);

}
$(document).ready(function() {
	if ($('.popup').length) {
		checkHeight();
		$('body').prepend('<div class="overlay HiddenImportant"></div>');
		$('html').click(function() {
			$('.popup,.overlay').addClass('HiddenImportant');
		});
		$('.popup, .table,.dscr h2 span').click(function(event) {
			event.stopPropagation();
		});
		$('.popup').css('margin-left', $('.popup').width() / -2);
		$('.dscr h2 span').click(function() {
			$('.overlay,.popup').toggleClass('HiddenImportant');
			$('.overlay').css('height', $('#wrapper').height() + 16);
		});
	} else {
		$('.popup, .table,.dscr h2 span').click(function(event) {
			event.preventDefault();
		});
	}
	$(window).resize(function () {
		setTimeout( checkHeight(), 1000);
	});
});

popup.css

.popup{
	position: absolute;
	top: 0px;
	left: 50%;
	background: #ffffff;
	box-shadow: 1px 1px 11px #444;
	z-index: 450;
	padding: 25px;
}
.overlay{

	position: absolute;
	background: black;
	opacity: 0.75;
	width: 100%;
	height: 100%;
	top: 0;
	left: 0;
	z-index: 400;
}
.popup h2{
	text-align: center;

}
/*
@media screen and (width<=1368px){
table.table td, .news_content table td {
padding: 3px 5px;
}
}
*/
.smallscreen table.table td, .smallscreen  .news_content table td {
	padding: 3px 5px;
}