Top Navigation taking over screen on cell phones

Hello!

I am having some trouble with the mobile version of my site. The main landing page looks fine on computer screens and tablets, but it completely glitches when someone goes to it on a cell phone. The menu pops up fine, but the text beside it separates. I’ve tried it on several different cell phones to make sure it wasn’t just an issue with my phone.

The site is: clintonpubliclibrary.org

I’ve looked at the resolution for mobile only, but I can’t find where in the code to fix this problem, or if it’s just a wordpress settings issue.

Please help or I’ll have to get a new theme (I REALLY don’t want to do that.)