Is there a way to control the Smoking not going above the stage?

Hi,

In the following example (File attached), the smoke goes above the stage. I want to avoid it, and limit the smoke to go maximum up to the stage.

I need it because my flash is auto re-sizable to the browser width & height. And when the smoke go above the stage my swf file starts shrink and gets very small.

How to solve this problem?

Please help.