change tagline font

Hi, I’d like to know how to change the font of my site tagline without affecting the rest of my site.

I’ve tried:

.site-description {
font-family: Geo;
}

in Additional CSS but it had no effect. Is there a way to do it? The font I would like to change it to is Geo from Google fonts.

The page I need help with: [log in to see the link]