When someone clicks on an image in one of the galleries (example can be seen here ) the image always scrolls to the bottom of the browser window instead of opening centered in the window. Any ideas as to what is going on?

Update*** The images are actually centering ... what is not centering is the overall window of the popup which is what I am wanting to happen. I have a discription and price below the image in the popup that I want to be centered along with the image  (the whole window) ..... right now what happens is the image gets centered which pushes the description to the bottom of the window and sometimes out of view. Is this possible to center the whole window?