Can't control "subdued" background color behind transparent thumbnails in order summary

Retired Boards Appdev Store Design
1

I’m using the new checkout extensibility admin API, specifically the checkoutBrandingUpsert GraphQL mutation in the Admin API. I’m seeing this style --x-default-color-background-subdued: var(–swn0jdn, var(–swn0j15)); (currently var(–swn0jdn) which is rgb(238,238,238) being applied) and I can’t find the corresponding color in the mutation fields. I need to change this value to migrate our checkout off of liquid. I simply need to know what value controls this in the graphQL mutation and I can change it myself.

Thanks!

Dan