The offline page for this site points to an image on "cdm.sstactic.net" for its background, but it should be "cdn.sstatic.net":
background: transparent url('http://cdm.sstatic.net/scifi/img/bg-site.jpg') repeat left top;
The background colour should likely also be specified as something dark, in case the image doesn't load for some reason, because of the light colour used for the text.