[jQuery] jQuery + FireBug: how to add '@media print' CSS?

[jQuery] jQuery + FireBug: how to add '@media print' CSS?

<div>Hi!
</div><div><br class="webkit-block-placeholder"></div><div>With FireBug (in Firefox) one can access the DOM of a page that is being viewed with the browser, and modify it on the fly.  I would like to take advantage of this capability to add the CSS directive '@media print { body { font-size: 12pt } }' to the document.</div>
<div><br class="webkit-block-placeholder"></div><div>Is there an easy way to do this with jQuery?</div><div><br class="webkit-block-placeholder"></div><div>I tried various alternatives, like</div><div><br class="webkit-block-placeholder">
</div><div><span class="Apple-style-span" style="font-family: 'courier new', monospace;"><span class="Apple-style-span" style="font-weight: bold;"><span class="Apple-style-span" style="font-size: large;">$( document ).attr( 'style', '@media print { body { font-size: 12pt } }' )</span></span></span></div>
<div><br class="webkit-block-placeholder"></div><div>but nothing seems to work...</div><div><br class="webkit-block-placeholder"></div><div>Thanks!</div><div><br class="webkit-block-placeholder"></div><div>kynn</div><div>
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