Sure, the Repository module is 'template' based, which means it uses external 'template' files to control the formatting of the output.
Templates are stored in the /DesktopModules/Repository/Templates folder and each template is in a sub-folder, so the 'default' template is in the default folder, etc.
Each part of the Repository is controlled by a pair of files, for example, the header is controlled by the header.html and header.xml files, and the main display part is controlled by the template.html and template.xml files.
The .html file controls the layout and contains HTML tags and special Repository tags. The Title of a Repository item is positioned in the template.html file using the [TITLE] tag. The .xml files allow you to assign attributes to the tags that are present in the .html file, so to change the formatting of the [TITLE] tag, you would edit the [TITLE] token in the template.xml file and add or change the CssClass Setting.
The default stylesheet class for the [TITLE] tag is "Head". If you wanted to use the 'SubHead" attribute for the title, add a Setting named CssClass and set the value to SubHead. Look in the template.xml file and you'll see what I mean.
if you want to define your own special stylesheet class to use for a tag, you can add the .class definition to your portal's portal.css file, or your skin's skin.css file, or even place the definition inline by adding it to the header.html file then setting your custom class as the CssClass value for the [TITLE] tag.