White/Empty Space -- Lightbox Issues

I have created a lightbox with several containers on it. Depending on the circumstance, some elements may expand or collapse. The issue is the height on the lightbox is static. So, if some elements are collapsed, there is excessive white space. Alternatively, if many of the elements are expanded, they fall outside of the lightbox.

Here is a screencast of the issue. Notice how when the elements are collapsed the button moves up but the actual lightbox bottom does not.

Anyone know how to fix?

[u]https://www.screencast.com/t/GOzM0XVH[/u]