How to apply a background color to a Card

[FDelporte]

In my UI I'm using a mix of atlantafx.base.controls.Card and atlantafx.base.controls.Message. The message boxes can be very beautifully styled with these styles:

    public static final String ACCENT = "accent";
    public static final String SUCCESS = "success";
    public static final String WARNING = "warning";
    public static final String DANGER = "danger";

Is there a way to apply the same styling to Cards? When I try to do this, it has no effect at all...