Themes
You'll want to set a "Theme" from a number of choices. Themes provide a consistent visual presentation for your site. You may choose from one of many themes included with your site, or have a custom theme developed for you by an outside designer.
Clicking on the Appearance button in the Control Panel lets you select a Theme. Changing the theme only effects the look and feel of your site, but not the content you've created. Your site's theme can be changed at any time.
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Read more about Managing the Look of Your Site