Changing Info box width in Lightbox

Hello!

I’d like to be able to control the default width and height of the infobox that appears in the Lightbox. It seems to be about twice the size of what I need and it overlaps many of the images that appear in the lightbox.

There doesn’t seem to be a parameter for controlling that in the Theme > Lightbox settings page. I can control the Infobox position, alignment, background colour, transparency, border, padding, margin, etc., but not the width or height.

Is there some simple custom CSS I could add to do that?

Thanks,
Alan.

The page I need help with: [log in to see the link]