Submit button colour custom CSS not working

Hi,
On the above site I’d like to change the colour of the submit button (bottom of page). I’ve found the element and changed the colour first in the “global” stylesheet, the in the form’s own Custom CSS &JS section but it gets overridden to the default blue colour. Could you please help what the problem can be?
I tried to post this to your website but it seems that only paying customers can have an account there…
Unfortunately I can’t attach a picture here…
I really appreciate your help.
Kind regards,
Rita

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