Alternate CSS Style
The Alternate CSS Style refers to the choices in the bottom half of Styles drop-down menu (on the toolbar) that makes it easy to apply style changes to your documents as they appear in Author mode and the output without having to edit the CSS stylesheets. By default, the alternate styles are applied like layers, they are merged sequentially with the main CSS style, and you can activate any number of them. However, if you deselect the Enable multiple selection of alternate CSSs option in the CSS subtab of the Document Type configuration dialog box, the alternate styles are treated like main CSS styles and you can only select one at a time.