function addClass(element, value) {
	if (!element.className) {
		element.className = value;
	} else {
		var newClassName = element.className;
		newClassName += " ";
		newClassName += value;
		element.className = newClassName;
	}
}



window.onload = function (){
	if ((screen.width<=1024) && (screen.height<=768)) {
		// Resolutions of 1024*768 or smaller
		//alert("1")
	}else{
		// Resolutions bigger than 1024*768
		//alert("2"+screen.width)
		addClass(document.getElementById('bg_wrapper'), 'bg_wrapper_morethan1024');
	}
}