How to style label attributes in Flex forms?

I've got FormItems with labels, and I'd like for the label to appear on top of the textinput within it rather than to its left, but I don't know where I need to go or what 开发者_如何学JAVACSS I need to set this.

<mx:Form id="myform" defaultButton="{BtnSave}">
  <mx:FormItem label="MyData" required="true">
    <s:TextInput id="dataTextInput" text="{data}"/>
  </mx:FormItem>
</mx:Form>

I don't think this is possible w/ MX Forms. I guess in theory you could do something like this:

<mx:Form id="myform" defaultButton="{BtnSave}">
  <mx:FormItem required="true" direction="vertical">
    <s:Label text="MyData" />
    <s:TextInput id="dataTextInput" text="{data}"/>
  </mx:FormItem>
</mx:Form>

But, If you're going to do that then why bother using the form in the first place?