How to change font size on secondary navigation bar?

Hi there, I have the Wells template. In Site Styles, I'm able to change the size/font of all navigation bars.

However, I'm trying to change the font size of just the secondary navigation bar. I've circled it in the attached image. 

Can anyone point me to the right CSS code to achieve this? Thank you all. 

Try entering the below into your websites CSS, just remember to adjust the font size to your desired size.

.main-nav .folder li a {font-size:9px!important}