Mushroom Cards - Build a beautiful dashboard easily πŸ„ (Part 1)

Hello, I try to get the moon phases picture on my HA. But I only get a black circle.

I try this code:

type: custom:mushroom-chips-card
chips:
              - type: template                
                style: |
                  ha-card {
                    --chip-background: url( {% set state = states('sensor.moon') %} /local/moon_phases/{{state}}.png ) no-repeat center center;
                  }

and this code:

type: custom:mushroom-chips-card
chips:
  - type: template
    card_mod:
       style: |
         ha-card {
           {% set phase = states('sensor.moon') %}
           --chip-background: url( '/local/moon_phases/{{ phase }}.png' ) no-repeat center center;
         }

But with both codes are only the black circle.

My pictures are 36 x 36 px and I save it under:
www/moon_phases/

If I enter the following adress in the browser:
https://homeassistant.local:8123/local/moon_phases/waxing_crescent.png

I see the picture. What make I wrong?