A content completion assistant similar to the one of XML documents offers the CSS properties and the values available for each property. It is activated on the CTRL + Space shortcut and it is context sensitive when it is invoked for the value of a property.
The properties and the values offered as proposals are dependent on the CSS Profile selected in the CSS Validator page, → +Profile combo box. The CSS 2.1 set of properties and property values is used for most of the profiles, excepting CSS 1 and CSS 3 for which specific proposal sets are used.