[SOLVED] Styling font size on caption for just one photo

I would like the make the caption font larger on just one photo, but can't seem to figure this out. Here's what I have tried:

div#attachment_594 .wp-caption-text {
font-size: 1em !important;
}

div#attachment_594 p {
font-size: 1em !important;
}

Can someone provide the proper code for me, because I'm not sure what else to try.

URL is http://www.reapfoundation.org/student-resources/. Atahualpa version 3.7.3, WP 3..3.1.

Thank you.