Adjusting text size of tagline in site identity

Is there a way to adjust the size of text in the tagline under the site identity without changing the text size throughout the site?

I added this to the CSS but it’s obviously not correct as it changed the tagline size as well as several other pieces of text throughout the site.

body, .site-description, .sidebar .featured-content .entry-title {

So I tried this and it was also incorrect.

body, .site-description {

Where is the best place to pull the appropriate CSS to change? Thanks!

https://www.whipandwander.com