I'm using the Berlin theme and noticed there's no header.php file to modify. Can I customize the header, when clicked, to bring visitors to site outside of Omeka?
We're essentially using Omeka as a back-end tool (more or less) and want to direct people back to another site's url.
Omeka themes are "sparse": files can be not present in a theme, and that will just cause Omeka to use a common fallback file instead.
These fallback files are located in application/views/scripts, and they would be your basis for modifying the theme. Copy the common/header.php file from there to your custom Berlin theme, and modify the copy as you wish.