The Style Designer is a fantastic way to individualize your site and make it stand out by enhancing some of the key elements on your site. The changes made through the Style Designer are done at the site-level. This means you only have to change the setting once and the changes will be applied to all your pages at the same time!
The Style Designer can be accessed by going to Style > Designer.
For more information about the various elements you can tweak, please see this tutorial: The Style Designer.