The Widescreen Template Set
It's called "widescreen" because it's a liquid layout that uses the entire screen width, rather than a fixed-width column. I'll attach some screenshots later.
Configuration
To use this as your default template set, set default_site_templates="widescreen" in your siteframe.ini file. This will use the templates unmodified.
Custom CSS. Widescreen allows you to specify an optional CSS file that you can use to override the base CSS and customize the appearance of the site. To provide your own custom CSS, create a CSS file somewhere in your web directory tree, then set the configuration value widescreen_css="/yourfile.css" in siteframe.ini. "widescreen_css" is a URL path that is used in the header of the generated web page, and not a directory path; for example, if your CSS is named example.css and you've placed it in the root of your web directory, the value should be /example.css.
Custom Background Image. You can specify the background image to be used for the header; set the property widescreen_header_background_image to the URL of the image you wish to use. For example, if you have "example.gif" in your images/ directory, your siteframe.ini would include this:
widescreen_header_background_image = "/images/example.gif"
To be most effective, the image should use a gradient that moves from 100% opacity at the background color on the left, to 0% opacity on the right. The image should be at least 100 pixels high. The default header background color is #eee, but you can change that using the custom stylesheet (above).

