window.onload = setScreenClass; 
window.onresize = setScreenClass;	

function setScreenClass(){
    var fmt = document.documentElement.clientWidth;
    var cls = (fmt<=800)?'screen_800':(fmt>800&&fmt<=1024)?'screen_1024':(fmt>1024&&fmt<=1280)?'screen_1280':(fmt>1280&&fmt<=1440)?'screen_1440':(fmt>1440&&fmt<=1600)?'screen_1600':(fmt>1600&&fmt<=1680)?'screen_1680':(fmt>1600&&fmt<=1920)?'screen_1920':'screen_1920';
    document.body.className=cls;
	//$('container').setStyle('height', document.documentElement.clientHeight);
	var container = document.getElementById("container");
	container.style.height=document.documentElement.clientHeight + "px";
};