Change background dinamically

[ajavibp]

Hi, I would like to be able to modify the background color based on an entity that tells me the price of electricity. The idea would be to do something like this, only this code doesn't work.
Is there any way to do it correctly?
Thank you very much.

style_card_content: |
background-color:
{%- set period = states.sensor.precio_kwh.attributes.Period %}
{%- if period == 'P3' %} #00ff000a
{%- elif period == 'P2' %} #ffb40010
{%- elif period == 'P1' %} #ff00000a
{%- else %}#006400
{%- endif %}