How do you resize the top menu items - they are too small

I've been through my website and changed most of the paragraph 2 sections to paragraph 1 which is a larger font.

I haven't been able to change the font size of the menu at the top of the page. It's really teeny. I've attached a screenshot. You can see the size of my H1 Title at left and the menu items in the upper right.

My website is not live yet.

Can anyone help me with the css code for this?

Thanks,
Susan

Thank you, Paul. I was able to change the font size from there.

Susan