改变富文本编辑器的表头样式

<?xml version="1.0" encoding="utf-8"?> 
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
        layout="vertical" 
        verticalAlign="middle" 
        backgroundColor="white"> 
  
    <mx:Style> 
        .richTextEditorTitleStyle { 
            color: haloBlue; 
            fontSize: 24; 
            fontWeight: bold; 
            textAlign: center; 
        } 
    </mx:Style> 
  
    <mx:RichTextEditor id="richTextEditor" 
            title="Rich Text Editor" 
            titleStyleName="richTextEditorTitleStyle" /> 
  
</mx:Application>