Home Joomla! - How do I? Change Joomla 1.5.x default site offline page
Change Joomla 1.5.x default site offline page

Backup these two files before making any changes!

The offline page that you need to modify is offline.php located in /templates/system/offline.php

The CSS file that goes with this offline page is located at /templates/system/css/offline.css