The actual chip background or the color of the card background?
The chip background would be
type: custom:mushroom-chips-card
chips:
- type: entity
entity: your.device
card_mod:
style: |
ha-card {
--chip-background: {{ 'lime' if is_state(config.entity, 'on') else 'red' }};
}
Check out this guide. It will give you an idea of what standard options are and where card-mod is required.