It is definitely not up to the official thermostart card to make sure it looks nice inside a custom layout card. That would be the job of the custom card, unless it also behaves bad in official layouts. So it is not a bug in the thermostat card.
I do not know about that specific custom layout card, it might be intended behavior. Maybe try putting a vertical stack in between?
You’re probably right. I edited my OP to remove that implication.
I seriously doubt it. I use that custom card all over and I’ve never seen anything like that with anything other than the thermostat card. But it’s also the only thermostat card I have since I just got the thermostat put in today and added the card.
I thought I’d ask to see if anyone had ever seen anything like this and fixed it.