I tried downloading jquery UI 1.8.7 and got a corrupted zip file. Tried 2 different themes, chrome, and firefox, all same result.
Terminal says:
$ unzip jquery-ui-1.8.7.custom
Archive: jquery-ui-1.8.7.custom.zip
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.