a4j:loadStyle is similar to the standard style tag with src attribute, but it allows to load a style sheet file from alternative sources like a jar file.

src attribute defines the context relative path to the style sheet file. Instead of html style tag it's not required to have a prefix in your application. The leading slash in the path means the root of the web context.

You can use "resource://" prefix to access the file using RichFaces resource framework. For example, if your css file is located inside the jar file and has a full path there: /org/mycompany/assets/css/common.css, you can point to it with:

Code
<a4j:loadStyle src="resource:///org/mycompany/assets/css/common.css" />

Richfaces allows to have a dynamically generated css file based on RichFaces skinnability feature. xcss is an XML formated css with some additional extensions. The following example shows how the look-n-feel of non-RichFaces components might be changed based on the selected skin. The panel with the form elements consists only of non-Richfaces component, but it is sensitive to the current skin.

Style demo