Auto adjust font size for smaller screens

Hello all

I am using a child theme based on Spirited-Lite, which is a responsive theme that automatically adjusts for different devices.

However, I noticed today that on my laptop, when I open a menu that expands the screen beyond its borders, you then have to scroll to the right to see all f the text. When you close the menu, it reverts to the original size.

I hope that makes sense.

My question is, how can I adjust my script/s so that instead of making the page scroll horizontally, it rather decreases font size so that everything still fits onto one screen?

My page is at https://www.entdocatiya.co.za, and the menu I am referring is “patient information –> Common condition/useful websites/ Procedures & surgeries”

Thank you