Changing product block background and color.

Site URL: https://www.cabalcult.com/merch

Hey everyone,

After a new update on the Squarespace template I've been using, the 'Add to Cart' area has been changed and now it doesn't work with my CSS coding.

Previously, I could add the following code to change the 'Select size' area to a black background with yellow letters (as the rest of the site):
select {
  background: #000;
  color: #f5f4b7;
}

It would apply across the site. My current problem is, that the selection doesn't even appear on the products anymore, and once I click the 'area where it is supposed to be', I get a grey box with white letters, not showing all size options.

Is there some way to fix it, so I can have i.e. a black background for the selection, and make it show up? 😮