// top navigation
function top_navigation(id)
{
        document.getElementById("home").className = "";
        document.getElementById("support").className = "";
        document.getElementById("services").className = "";
        document.getElementById("media").className = "";

        document.getElementById(id).className = "current";

        document.getElementById("home_links").className = "";
        document.getElementById("support_links").className = "";
        document.getElementById("services_links").className = "";
        document.getElementById("media_links").className = "";

        document.getElementById(id + "_links").className = "current";

}