Changing width of Add Items page

Hello

I have installed Gallery 2.2.2 and all working well. I have embedded in Joomla and all working well except I would like to change the width of the Add Items page so it does not go beyond my template and look dodgy.

See attachment for example of how it looks. I want to make it just wide enough so I don't get the overlap.

Your help is appreciated.

Gallery version = 2.2.2 core 1.2.0.4
PHP version = 5.2.0 apache
Webserver = Apache/1.3.37 (Unix) PHP/5.2.0 mod_jk/1.2.14 mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 FrontPage/5.0.2.2635.SR1.2 mod_ssl/2.8.28 OpenSSL/0.9.7a
Database = mysqli 4.1.21-standard, lock.system=flock
Toolkits = Exif, Gd, ArchiveUpload, SquareThumb
Acceleration = none, none
Operating system = Linux zeus.serversaustralia.com.au 2.6.9-42.0.3.ELsmp #1 SMP Fri Oct 6 06:21:39 CDT 2006 i686
Default theme = matrix
gettext = enabled
Locale = en_US
Browser = Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4
Rows in GalleryAccessMap table = 16
Rows in GalleryAccessSubscriberMap table = 64
Rows in GalleryUser table = 30
Rows in GalleryItem table = 64
Rows in GalleryAlbumItem table = 4
Rows in GalleryCacheMap table = 0