How can I change the Quantity label on Squarespace products?

If you want to rename the ‘Quantity:’ label on a Squarespace Product Detail Page, add this to Design > Custom CSS and edit the text within the quotes to suit your requirements:

/************************************** 
Change Product Quantity label
Copyright SF Digital https://sf.digital
Use freely in your Custom CSS but  
do NOT re-publish.
**************************************/
.ProductItem-details .variant-option-title, .ProductItem-details .variant-out-of-stock, .ProductItem-details .quantity-label {
    visibility: hidden;
}
.ProductItem-details .variant-option-title, .ProductItem-details .variant-out-of-stock, .ProductItem-details .quantity-label:before {
    content: "# of travelers:";
    visibility: visible;
}