CSS style by ID
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical"> <mx:Style> @namespace mx "http://www.adobe.com/2006/mxml"; .header { font-family: 'Arial'; font-size: 15px; font-weight: 'bold'; color: #FFFFFF; } </mx:Style> <mx:VBox id="holder" width="200" height="200"> <mx:Label id="labelField" text="Hello Flex!" styleName="header" /> <mx:Button label="Button" /> </mx:VBox> </mx:Application>