Can you select non-breaking spaces in CSS?

function user_content_replace($content) {
return str_replace(‘<p> </p>’,'<p class=”example”> </p>’,$content);
}
add_filter(‘the_content’,’user_content_replace’, 99);

Class ‘example’ is aded in this way.

FSORCE: http://stackoverflow.com/questions/14703924/jquery-select-paragraphs-that-only-contain-nbsp