function initBubble() {
    setTimeout(showBubble,800);
}

function showBubble() {
    $('bubble').style.display = '';
    var fx = new Fx.Tween('bubble');
    fx.start('opacity',0.0,1.0);
    setTimeout(hideBubble,10000);
}

function hideBubble() {
        var fx = new Fx.Tween('bubble');
        fx.start('opacity',1.0,0.0);
}