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No, you cannot add a separate stylesheet to an element.
You can use inline styling via the style attribute.
<div style="font-family:arial;"></div>
http://www.w3.org/TR/REC-html40/present/styles.html#h-14.2.2
Better yet, dynamically add a specific class based on the user input and style it in the global stylesheet.
Source:stackexchange.com