There are four levels to a Drupal Lite page. When you are working on your site, you will be interacting with the last three in the list.
The Drupal Lite theme contains the majority of the CSS, code, and design elements. It also places the University of Minnesota Header and footer on the page.
The site-wide template is the level that distinguishes your site from others. This template has the elements that are unique to your site and that appear on every page.These include the Site Header and Footer (the items found in Custom Settings), as well as the site’s navigation menu.
The content regions are defined by the page layout. There are many different layouts available. Each content type has a default page layout for the content region, and each region has a default style. For each of your pages, you can change the page layout and/or change the style of a content region.
The final level are the actual content panes. Each content pane has default styling, but can be changed using the Customize This Page tool. Additional content can be added to a page using the same Customize This Page tool.