// JavaScript Document
function changeTab(id) {
    var divid = "div_" + id;
    var obj = document.getElementById(id);
    var div = document.getElementById(divid);

    document.getElementById("tab1").className = "tab_inactive";
    document.getElementById("tab2").className = "tab_inactive";
    document.getElementById("tab3").className = "tab_inactive";

    document.getElementById("div_tab1").style.display = "none";
    document.getElementById("div_tab2").style.display = "none";
    document.getElementById("div_tab3").style.display = "none";

    obj.className = "tab_active";
    div.style.display = "block"
}