function getWindowHeight() {
	var windowHeight=0;
	
	if (typeof(window.innerHeight)=='number') {
		windowHeight=window.innerHeight;
	}
	else {
		if (document.documentElement && document.documentElement.clientHeight) {
			windowHeight=document.documentElement.clientHeight;
		}
		else {
			if (document.body && document.body.clientHeight) {
				windowHeight=document.body.clientHeight;
			}
		}
	}
	
	return windowHeight;
}

//sets the absolute position of our footer based on our content or window height	
function setFooter() {
    var windowHeight=getWindowHeight();
		
		if (windowHeight>0) {
			    
			var footerElement = document.getElementById('footer');
			var contentHeight = getHeight();
			
			footerElement.style.position='absolute';
				
		    if (windowHeight > (contentHeight + footerElement.offsetHeight)){
		        footerElement.style.top = (windowHeight-footerElement.offsetHeight) + 'px';
		    }
		    else {
		        footerElement.style.top = contentHeight + 'px';
		    }			
		
		}else {
			footerElement.style.position='relative';
		}
}

//Gets the height of our content (includes header)
function getHeight(){
    var headerElement= document.getElementById('header');
    
    if (document.getElementById('side_panel').offsetHeight > document.getElementById('main').offsetHeight){
        return document.getElementById('side_panel').offsetHeight + headerElement.offsetHeight;
    }else{
        document.getElementById('footer').style.position='absolute';
       return document.getElementById('main').offsetHeight + headerElement.offsetHeight;
    }
}

window.onload = function() {setFooter();}
window.onresize = function() {setFooter();}