window.onload = checkAvailableWidth;
window.onresize = checkAvailableWidth;
function checkAvailableWidth(){
	var container = document.getElementById("mainnav");
	mainnav.style.width = (document.body.clientWidth < 1000)? "1000px" : "100%";
	var container = document.getElementById("headernav");
	headernav.style.width = (document.body.clientWidth < 1000)? "1000px" : "100%";
}