Picture Glance Image Background Transparency

Configuration Frontend
1

I’m looking to use Picture Glance Images to show power-generation from my solar panels.

I’d like to use Image Transparency Alpha channel to show the current power output.

I’m having trouble getting the Entity value to passthrough to the Background.

This works:

type: picture-elements
image: https://andyland.duckdns.org/local/RoofOutline.png
title: Roof
elements:
  - type: image
    image: https://andyland.duckdns.org/local/panel.png
    entity: sensor.panel_a1_power
    style:
      top: 21%
      left: 42%
      width: 6%
      transform: translate(0%, 0%)
      background-color: rgba(255,0,0,.9)

image

But this doesn’t:

image: https://andyland.duckdns.org/local/RoofOutline.png
title: Roof
elements:
  - type: image
    image: https://andyland.duckdns.org/local/panel.png
    entity: sensor.panel_a1_power
    style:
      top: 21%
      left: 42%
      width: 6%
      transform: translate(0%, 0%)
      background-color: rgba(255,0,0,."$ states('sensor.panel_a1_power')|int/255)")

I do not get any background-color value in my CSS.
image

image

What is the correct way to passthrough entity value to a background color alpha channel?