Change background color of thank you page - card format

in the forum i see help answers that show a screen for modifying a thank you page, similar to this box with options like bold italics color link etc.  When I edit my Thank You page though, I get no options except to change the text. Is it because I'm using the new card format?

For card forms, in the Form Designer Custom tab, there is option for change background color.

that will also affect the Thank You page background color.

So far that is the only method available for changing the card form background color of TY page.

Let us know if you require further assistance.