Default template plugin is included with CB at the following location.
/components/com_comprofiler/plugin/templates/default
It's a complete valid and installable plugin. The php file and xml file for your template should match the template name. The XML file needs to be updated with your template name for the plugin row. The PHP file also needs its PHP classes changed as they also include the template name.
If you're just wanting to do CSS overrides though I highly suggest just using the CSS override functionality below.
www.joomlapolis.com/blog/kyle/18711-template-css-overrides-made-easy