Change the font and/or edit the style of the entire drop down options for products, Squarespace 7.0

Site URL: https://www.inkandseal.co.uk/shop

How you can change the font and/or edit the style of the entire drop down options for product variants? There isn't an option in design site styles and I can't seem to access custom CSS on my 7.0 site. There must be a way to change the variant dropdown menu font from this serif font to one that matches the other fonts in the site

You can use this code to Website Tools (under Not Linked) > Page > Custom CSS

div.variant-option * {
    font-family: proxima-nova !important;
}