function getBrowserHeight() {
var intH = 0;
var intW = 0;

if(typeof window.innerWidth == 'number' ) {
intH = window.innerHeight;
intW = window.innerWidth;
}
else if(document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) {
intH = document.documentElement.clientHeight;
intW = document.documentElement.clientWidth;
}
else if(document.body && (document.body.clientWidth || document.body.clientHeight)) {
intH = document.body.clientHeight;
intW = document.body.clientWidth;
}
return { width: parseInt(intW), height: parseInt(intH) };
}

function setLayerPosition() {
var shadow = document.getElementById('shadow');
var question = document.getElementById('question');

var bws = getBrowserHeight();
shadow.style.width = bws.width + 'px';
shadow.style.height = bws.height + 'px';
question.style.left = parseInt((bws.width - 350) / 2)+ 'px';
question.style.top = parseInt((bws.height - 200) / 2)+ 'px';
shadow = null;
question = null;
}

function showLayer() {
setLayerPosition();

var shadow = document.getElementById('shadow');
var question = document.getElementById('question');

shadow.style.display = 'block';
question.style.display = 'block';

shadow = null;
question = null;
}

function hideLayer() {
var shadow = document.getElementById('shadow');
var question = document.getElementById('question');

shadow.style.display = 'none';
question.style.display = 'none';

shadow = null;
question = null;
}

window.onresize = setLayerPosition;