The CSS tool is accessed from the Admin page. It enables you to create and install style sheets for the CKEditor editing window.
Current Template
Using the CSS tool you can create a style sheet for the CKEditor's editing window that is based on your template. It will place the style sheet in your template folder in the directory named Styles, which will be created when the style sheet is saved. The style sheet will be named _styles.css. To activate this style sheet two things must be done:
Configuration Settings
must be set to true.
Other templates: installed but not activated
You can also create additional style sheets for other templates which you might have stored in your tpl folder. These will be copied to the Styles folder of the respective templates but not to ckeditor/css.
These can be compressed. See compression.