The Preferences dialog box's CSS Styles category controls how Dreamweaver creates and edits CSS Styles. Also see Chapter 10.
When Creating CSS Styles: Use Shorthand For
Create CSS Styles using the shorthand notation for Font, Background, Margin and Padding, Border and Border Width, and List-Style attributes. For example, when this preference is enabled, Dreamweaver creates font settings as properties of the font tag instead of individual CSS attributes such as font-style , font-width , and font-variant .
When Editing CSS Styles: Use Shorthand
Determines whether and how Dreamweaver updates CSS Styles when editing an existing document.
If Original Used Shorthand
If the original document did not use shorthand properties, Dreamweaver doesn't convert them to shorthand properties.
According to Settings Above
Dreamweaver overwrites existing CSS properties according to the settings for the "When Creating CSS Styles: Use Shorthand For" preferences.