Hello,Maddy!
1. Just set the smaller Font size in the custom CSS code I gave you previously.
2. You should be able to insert the same Logo image and set the smaller size for the Tablet/Mobile view, from Customizing->Logo->Mobile logo menu
https://prnt.sc/spma2p
Please let me know if this option for some reason don’t work for you, and I will give you the right code to fix that.
Regards