function ajustaCamada(){
  var largura_tela_utilizavel = document.body.clientWidth; // FUNCIONOU EM TODOS OS BROWSERS
  document.all['banner'].style.left             = parseInt(largura_tela_utilizavel/2) - 101;
  document.all['menu_lateral'].style.left       = parseInt(largura_tela_utilizavel/2) + 205;
//  document.all['banner'].style.visibility       = 'visible';
  document.all['menu_lateral'].style.visibility = 'visible';
}

function alternaCamada(status){
  if(status == 'on'){
    document.getElementById('banner').style.zIndex = 2;
    document.getElementById('menu_lateral').style.zIndex = 1;
  }else if(status == 'off'){
    document.getElementById('banner').style.zIndex = 1;
    document.getElementById('menu_lateral').style.zIndex = 2;
  }
}