You can create a CSS rule to automate the formatting of HTML tags or a range of text identified by a class attribute.
Select Text > CSS Styles > New.
In the CSS Styles panel (Window > CSS Styles), click the New CSS Rule (+) button located in the lower-right side of the panel.
To create a custom style that can be applied as a class attribute to a range or block of text, select the Class option and then enter a name for the style in the Name text box.
To redefine the default formatting of a specific HTML tag, select the Tag option and then enter an HTML tag in the Tag text box or select one from the pop‑up menu.
To define the formatting for a particular combination of tags or for all tags that contain a specific Id attribute, select the Advanced option and then enter one or more HTML tags in the Selector text box or select one from the pop‑up menu. The selectors (known as pseudo‑class selectors) available from the pop‑up menu are a:active, a:hover, a:link, and a:visited.
To place the style in a style sheet that is already attached to the document, select the style sheet.
To create an external style sheet, select New Style Sheet File.
To embed the style in the current document, select This Document Only.