Edit online

The rendering of an HTML document in the Author mode is driven by a CSS stylesheet that conforms to the version 2.1 of the CSS specification from the W3C consortium.

To associate a CSS with an HTML document:
  1. Use the Associate XSLT/CSS Stylesheet action that is available on the toolbar or in the XML menu.
  2. In the resulting dialog box, specify the URL for the CSS file and optionally a title, and click OK.

Result: A CSS association is added in the HTML document in a <link> element, as specified in the W3C stylesheet specification.