if (screen.width==800){

document.getElementById('topo').style.margin = "0 0 0 -440px";
document.getElementById('menu').style.margin = "0 0 0 -360px";
document.getElementById('centro').style.margin = "0 0 0 -450px";
document.getElementById('centrofundo').style.width = "1000px";
document.getElementById('rodape').style.width = "1000px";

document.getElementById('menudiv2').style.marginLeft = "-262px";
document.getElementById('menudiv3').style.marginLeft = "-165px";


}