@warrencowan83. Are you talking about the Bootstrap modal that I used as the default preview modal?
There are 2 modals you can use. One is the Mootools modal that existing since Joomla 1.5, and the other is the Bootstrap modal that was added since Joomla 3.0. The Bootstrap modal seems to have a fixed width and height. I tried to make it configurable, but it really wasn’t designed that way. So, to avoid possible issues, I left it alone. I guess you could alter the css, but I would avoid that.
Have you tried using the Mootools modal?