#container shifts to the left after third #btnAdd click?

I have no idea why this happens, but after clicking #btnAdd for the third time and ad开发者_如何转开发ding the third set of form elements, the entire #container structure moves slightly to the left.

Here's my JSBin (JsFiddle is down): http://jsbin.com/enowiv/edit#javascript,html

Does anyone know why this is?

Comments, thoughts and of course, answers would be greatly appreciated :)!!

It's because the vertical scrollbar is showing on the third click.

You can get it to always show by using the CSS:

body {
    overflow-y: scroll;
}