How to add icon to secondary information field

Current Behavior

This is not really a bug but rather a question and I did not find a better place where to post it:

I use a template card on my dashboard.

I use the following code to display the number of open windows on that card as secondary information:

{%set state=states(‘sensor.office_open_windows’)%}{% if state | int >= 1 %} W: {{ state }}{% else %}{% endif %} So if e.g. one window is open it displays “W: 1”. So far so good. However it would look cooler if instead of the W I could display a mdi:window-open icon in front of the counter.

I tried adding mdi:window-open in various ways but I could not get it to work. Btw. I am happy with a static icon, does not have to be dynamic.

Expected Behavior

No response

Steps To Reproduce

No response

Environment

- OS:
- Node:
- Version:
- Hassio:

Anything else?

No response

[hesspoint]

I used the window one and the plant. so if at least one window/door in that room is open and/or at least one plant low on water it will show the icon with the number of affected entities.

[hesspoint]

I simply did a linebreak in the secondar information field. Every new line in the code is also a new line in the UI. So if you have e.g an if else statement you need to write it all in one line. If you break it into multiple lines as I normally would it will create a bunch of blank lines.