adding 'posted' before date

I got this working by editing the plugin, and changing:
echo '<h2'.$h2_classes.'><a href="'.get_permalink().'">'.get_the_title().'</a></h2>';
to
echo '<h2'.$h2_classes.'><a href="'.get_permalink().'">'.get_the_title().'</a></h2>Posted on ';

I think I should be able to do this with css, but I haven’t been able to figure it out.
I’d prefer not to edit the plugin, so if someone has a suggestion, I would appreciate it.
Susan

Hi, Susan! You can do this in CSS like so:

.recent_posts_with_excerpts h3.date:before {
   content: 'Posted on: ';
}