laid back
Someone who’s always chill, never argues, and will even argue about something that’s not important, but in a chill way.
My brother is laid back. He’ll sit there and not say a word, even if the whole house is on fire.
My friend is laid back, so he doesn’t care if we’re late for everything.
My neighbor is laid back. He even argues about the mailman’s name in a calm, relaxed way.