Mushroom chip card entity change icon color with state change

I am trying to make a cleaner mobile dashboard using mushroom chips card.
I would like to have the color of the switch.blueiris_schedule_away icon change based on the state of the switch. I have tried many things and it just remains white.

Here is my latest try… what am I missing here?

type: custom:mushroom-chips-card
chips:
  - type: back
  - type: spacer
  - type: weather
    entity: weather.forecast_home
    show_temperature: true
    show_conditions: false
  - type: spacer
  - type: entity
    entity: switch.blueiris_schedule_away
    tap_action:
      action: toggle
    card_mod:
      style: |
        :host {
          --icon-color: 
            {% if is_state('switch.blueiris_schedule_away', 'on') %}
              green
            {% else %}
              gray
            {% endif %};
        }
  - type: entity
    entity: switch.blueiris_schedule_day_night
    tap_action:
      action: toggle
  - type: spacer
  - type: menu
alignment: justify

(I have read this page: Mushroom Cards Card Mod Styling/Config Guide)

what is curious to me, is that if I just use a button within a horizontal stack card that the icon changes color based on state and I am not even specifying that behavior. (Here with At Home “on” and Away “off”)

type: horizontal-stack
cards:
  - show_name: true
    show_icon: true
    name: Away
    entity: switch.fincajill_schedule_away
    type: button
    tap_action:
      action: toggle
    show_state: false
  - show_name: true
    show_icon: true
    name: At Home
    entity: switch.fincajill_schedule_day_night
    type: button
    tap_action:
      action: toggle
    show_state: false

Any help getting this working would be greatly appreciated!

Then probably that thread would be a better place to ask a question? Many users are subscribed to that thread & may come to help.

I could not find a “new topic” button there…