Taxonomy term description with style, only if the description exists?

term_description() returns a string, which might be empty.

So the test should be:

$term_desc = term_description();
# debug
print '<pre>' . htmlspecialchars( print_r( $term_desc, TRUE ), ENT_QUOTES, 'utf-8', FALSE ) . '</pre>';

if ( '' !== $term_desc )
{
    echo "<div id='term-desc'>$term_desc</div>";
}