var iD = "navi";

// ======== setting variable ===========

var balloons = getElementsByClassName("balloon");
var e_lists = getList(balloons);

// ========= set events ================

for ( var i = 0 ; i < e_lists.length ; i++ ) {
    e_lists[i].onmouseover = new Function ('','balloons[' + i + '].style.visibility="visible";');
    e_lists[i].onmouseout = new Function ('','balloons[' + i + '].style.visibility="hidden";');
}

// ================ lib ================

function getList(e) {
    var l = new Array();
    for ( var i = 0 ; i < e.length ; i++ ) {
        l[i] = e[i].parentNode;
    }
    return l;
}


function $ (str) {
    return document.getElementById(str);
}

function getElementsByClassName  (str) {
    var childs = document.getElementsByTagName("*");
    var pattern = new RegExp('(^| +)' + str + '( +|$)');
    var r = new Array();
    var j = 0;
    for ( var i = 0; i < childs.length; i++ ) {
        if ( pattern.test(childs[i].className) ) {
            r[j] = childs[i];
            j++;
        }
    }
    return r;
}