Change caption font when "click to enlarge" a gallery photo

Hi! I'm trying to change the font when you click to enlarge a photo in a gallery. See attached screenshot.

I added a custom font for Header 1 and that is the font showing up in the enlarged photo caption. The problem is that it is small and difficult to read. I'd like to change it to H2. Squarespace support could not help and suggested I try here. They said i may have to edit the custom CSS to change it, but when i looked, it seems like it would change the H1 font on the entire site.

TLDR: So basically I need to change the font in the enlarged photo caption from H1 to H2.

You can see here: www.iglamlab.com > About > Team > click to enlarge one of the photos in the gallery and see caption font.

Add to Home > Design > Custom CSS

.sqs-lightbox-meta h1 {
    font-size: 30px !important;
}