It works, but the "IFRAME" isn't growing because you have a bunch of gobbly goop in there. You can see it is working, though because if you click in there and drag down your mouse it actually scrolls down and you see the login boxes.
Rather than start with your existing page and put the Third Party Login html in there, it is better to start with Third Party Login html and slowly put your header into it (i.e. do what you did in vise versa).