Implement real cascading or child selectors for CSS in AS3

We all know there's CSS support in AS3. But 开发者_StackOverflow社区actually it's not CSS, but just SS. Is there a way to implement cascading?

For example I have

Compare <em>regular italic</em> and <strong>bold text or event <em>bold italic.</em></strong>

How can I define special fonts for regular italic and strong italic?

upd: or how is it named? Basically "How to make styles for child selectors work?"

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I'f you're using Flex an upgrade to flex 4 will solve it. https://bugs.adobe.com/jira/browse/SDK-14385

If you're using Flash, no idea!