You are not using the correct fields for the font.
type: custom:mushroom-light-card
entity: light.pc_lights
card_mod:
style: |
ha-card {
background: grey;
--card-primary-color: orange;
--card-secondary-color: red;
}
Going forward, I would ask Mushroom related questions in the main Mushroom thread as Sir_Goodenough mentioned.
In addition it is helpful if you post your code using the forum standard. Check out #11
It allows folks that assisting to easily copy and past your code.