function hideSubMenus()
{
    document.getElementById("menuempresa").className = "invisivel";
    document.getElementById("menuservicos").className = "invisivel";
    document.getElementById("menuportfolio").className = "invisivel";
    document.getElementById("menulocalizacao").className = "invisivel";
}

function showSubMenu(menu)
{
    hideSubMenus();

    document.getElementById(menu).className = "visivel";
}