Help with template syntax please

Sorry this might be easy, but I really struggle with (what feels at least) really odd syntax variations - as an aside if anyone can recommend some good guides to the vaguaries of using HA templating / Jinja2 that would be great.

My current challange is I am trying to make a situation where the styling (specifically background-color) fon a card is dependant on whether or not a particular entity_id is part of a group.

I have seen and successfully used something which changes the background-color to the rgb value if a light is switched on, using the following:

type: custom:config-template-card
entities:
  - light.study_lights_group
  - group.dynamic_lights
card:
  type: picture-elements
  image: local/floorplan_ground2.png
  elements:
    - type: image
      image: /local/study.png
      style:
        background-color: >-
          ${var light_rgb='252, 3, 140';  if
          (states['light.study_bl'].state == 'on') 'rgba('+light_rgb+',1)'; 
          else 'rgba(0,0,0,0)';}
        top: 35.45%
        left: 77.85%
        width: 23.1%
        transform: rotate(-90deg)
      entity: light.study_lights_group
      tap_action:
        action: call-service
        service: script.group_change
        service_data:
          selected_light: light.study_lights_group

but I cannot work out how to incorporate this with the template approach for checking if a string is “in” an attribute. i.e. this resolves correctly in developer mode:

{% if "light.study_lights_group" in state_attr("group.dynamic_lights","entity_id") %}

but I don’t understand how to lift and shift that into my card. For example this doesn’t work:

    - type: image
      image: /local/study.png
      style:
        background-color: >-
          ${var light_rgb='252, 3, 140';  if 
          "light.study_lights_group" in state_attr("group.dynamic_lights","entity_id") 
          'rgba('+light_rgb+',1)'; else 'rgba(0,0,0,0)';}
        top: 35.45%
        left: 77.85%
        width: 23.1%
        transform: rotate(-90deg)
      entity: light.study_lights_group
      tap_action:
        action: call-service
        service: script.group_change
        service_data:
          selected_light: light.study_lights_group

Or if I simply further …

card:
  type: picture-elements
  image: local/floorplan_ground2.png
  elements:
    - type: image
      image: /local/study.png
      style:
        background-color: >-
          ${if  ("light.study_lights_group" in
          state_attr("group.dynamic_lights","entity_id") == 'True') 'rgba(252,
          3, 240, 1)';  else 'rgba(0,0,0,0)';}
        top: 35.45%
        left: 77.85%
        width: 23.1%
        transform: rotate(-90deg)
      entity: light.study_lights_group
      tap_action:
        action: call-service
        service: script.group_change
        service_data:
          selected_light: light.study_lights_group

I have tried a variety of options for ’ " and { but since I am just shooting in the dark and nothing worked I am appeallng to the hive mind for guidance!

Thoughts appreciated
S