Box with fixed height

I installed the plugin “Fancybox for wordpress” and on the page https://ayisiandco.com/events/forum2013/partners/ when you click on any of the 3 images and pop-up appears, the text box has the text size instead of a fixed size. I tried to fix it by entering the settings section, then in the Miscellaneous tab and once inside putting a fixed height of 480 pixels.

Is there any other way to solve this problem?

http://ww.wp.xz.cn/plugins/fancybox-for-wordpress/