Resize shop titles in smaller screens

Site URL: https://dandelion-cowbell-5hbk.squarespace.com/config/?frameUrl=/shop

Hello, I've noticed that if I resize my web into what could be a tablet size, the titles of the shop products remain big and go out of the frame. I was wondering how I could make my code work to control the size of the text depending of the size of the screen. I am happy with how it looks in Mobile, it is just before it makes the swift it is too big. 

My current code is:

/*title shop overview*/
.ProductList .ProductList-grid .ProductList-item .ProductList-overlay .ProductList-title {font-family: 'Schnyder';
 }

I am trying to merge it with

@media only screen and (max-width: 640px) {  size: 8 px !important; }

But it doesn't work.

Could anyone help me? thanks in advance

Password: "skeuo"

/config is url for site owner.

Can you share link to exact page?

size is incorrect code, use font-size: 1em !important;

you can adjust 1 to 2,3,4,..

Thanks so much