To change the background black colour:
Open lightbox.css then find: (replace the red text with the colour of your choice)
Code:
#overlay{ position: absolute; top: 0; left: 0; z-index: 90; width: 100%; height: 500px; background-color: #000000; }
To change the white parts:
Find in the same file: (again change the red text to your colour of choice)
Code:
#outerImageContainer{ position: relative; background-color: #000000; width: 250px; height: 250px; margin: 0 auto; }
and
Code:
#imageDataContainer{ font: 10px Verdana, Helvetica, sans-serif; background-color: #000000; margin: 0 auto; line-height: 1.4em; overflow: auto; width: 100%; }
Hope that helps.