Themes are used to define a particular look and feel for Confluence. Use themes if you want to add a new functionality or to significantly alter the appearance of Confluence. Themes can be applied to the whole site or to an individual space.

Creating a theme consists of two steps:

1. Theme Writing with decorators and colour schemes, which defines how each page looks (see below).
2. Making your theme into a plugin - themes are part of our plugin system. Simply write an atlassian-plugin.xml file, zip it up into a .jar file, put it on the server's classpath, and your theme can then be loaded into Confluence.
   or the site, and any number of layout modules.

To install it within Confluence, please read Installing and Configuring Plugins.

There are also example themes for you to learn from and extend.

You may also want to read Including Cascading Stylesheets in Themes