Hi Colleen,
Disclaimer: This is based on my experience with Neatline Time, but it should work the same for any plugin. Also, I've been using Omeka for approximately 2 weeks. ;)
The easiest way to keep track of theme tweaks for plugins is to either hard code the CSS into the template in question (for exhibits, this would be themes/themename/exhibit-builder/exhibits/show.php) or to override the styles with a custom CSS file (stored in /themes/themename/css/).
This mitigates the possibilities of editing the wrong file or losing the customizations during an upgrade.
It looks like the class in question is "exhibit-text" as applied to a div. I found this as r b described, but in Firefox. In the code inspector, I added "style="padding-left: 100px;" to the code and it worked, so here's hoping! In the text editor of your choice, try
div.exhibit-text {
padding-left: 100px !important;
}
Replacing "100px" with your desired padding.
If you save these changes in a file called exhibit_fix.css in the theme's CSS folder, you would add the line
<?php queue_css_file('exhibit_fix');
echo head_css(); ?>
To the file /themes/themename/exhibit-builder/exhibits/show.php
Note, however, that this will only add padding to the exhibit text. To include all content, it may well be easier to do something like
#content {
padding-left: 100px !important;
}
Which will pad everything in the content area.