I have just purchased the pro-version for Visual Composer.
Tried setting the container height by using the class name as stated in your docs.
" fb3d-h-x " where x = heights in px (tried many values, 500, 600, 700 ....)
Nothing works. As a result i get a small thumbnail size of the PDF book. After checking the css properties in the developer tools. I noticed the container does not have a height set. instead the outer container carries a 900 by default. I am using the :the7" theme.
These styles for fullscreen mode. Use custom image as the book thumbnail. see also advanced tab of insert dialog.