Change the text on Product Blocks

Site URL: https://www.karastone.com.au/best-sellers

Hi there! 

I need a hand with some custom code to change the text size on the product blocks on this page https://www.karastone.com.au/best-sellers - the size of the text is showing larger than on product pages and i'd like it to be consistent. 

I used this code to reduce the size (which looked like it worked when i am in squarespace but when i view it outside of the squarespace platform, it doesnt look like the code has applied)

#collection-5fc8ad8ab0f45b2a3d2b3c88 {
  color: #000000;
  font-size: 11px;
}

What am i doing wrong? 

Help please 🙂

Add to Home > Design > Custom CSS

.product-block .productDetails .product-title {
    font-size: 1em;
}