In Dreamweaver CC and later, CSS Styles panel is replaced with CSS Designer. For more information, see CSS Designer.
When you edit an external CSS style sheet, all documents linked to that CSS style sheet are updated to reflect those edits. You can export the CSS styles found in a document to create a new CSS style sheet, and attach or link to an external style sheet to apply the styles found there.
You can attach to your pages any style sheet that you create or copy into your site. In addition, Dreamweaver is shipped with prebuilt style sheets that can be automatically moved into your site and attached to your pages.
To create a link between the current document and an external style sheet, select Link. This creates a link href tag in the HTML code, and references the URL where the published style sheet is located. This method is supported by both Microsoft Internet Explorer and Netscape Navigator.
You cannot use a link tag to add a reference from one external style sheet to another. If you want to nest style sheets, you must use an import directive. Most browsers also recognize the import directive within a page (rather than just within style sheets). There are subtle differences in how conflicting properties are resolved when overlapping rules exist within external style sheets that are linked versus imported to a page. If you want to import, rather than link to, an external style sheet, select Import.
For more information on media-dependent style sheets, see the World Wide Web Consortium website at www.w3.org/TR/CSS21/media.html.