Alternative background colours

[RexNoctis]

Would it be possible to have an option to change the background colours for different states?

I have found this code in the .js file but altering the '--thermostat-off-fill' and '--thermostat-idle-fill' does not appear to change the dial as I would have expected;

      .dial {
        user-select: none;
        --thermostat-off-fill: #222;    //Originally #555
        --thermostat-idle-fill: #555;   //Originally #222
        --thermostat-path-color: rgba(255, 255, 255, 0.3);
        --thermostat-heating-fill: #e36304;
        --thermostat-cooling-fill: #007af1;
        --thermostat-path-active-color: rgba(255, 255, 255, 0.8);
        --thermostat-path-active-color-large: rgba(255, 255, 255, 1);
        --thermostat-text-color: white;
        --thermostat-toggle-color: grey;
        --thermostat-toggle-off-color: darkgrey;
        --thermostat-toggle-on-color: lightgrey;
      }

Is this something that could be configured in the card configuration or am I doing something dumb?