WordPress.org

Companion is intended to assist users designing their sites without editing their original style.css files.

Companion's features include:

• Editing CSS stylesheets that override the original style.css in the theme.
• Add custom information into the head area of your site/page for non-wpmu sites. - Does NOT activate for Multisite

Please do *not* copy the entire style.css into the editor, the editor is used for placing specific element changes. If you want to change the background of your entire site you do

body { background: #333333; }

Notice that you do not need to replace the entire CSS element but just the portion you want to override / change.