Add buttons for predefined brightness to entities card

Throwing an in a few more options:

You can continue your current method and use card-mod to tweak styles.

You could use a grid instead of the footer. You can’t span columns, so the top entity and the grid below it might not look connected/united in a way you like. There’s an alternative though.

Then there’s the incredibly flexible custom button card where you can have buttons in buttons. It will be a bit of work though.