Is celo a layer 1 or 2?

Could you please clarify whether Celo is categorized as a Layer 1 or Layer 2 blockchain solution? I understand that Layer 1 blockchains are the foundational blockchains that host smart contract platforms and decentralized applications, while Layer 2 solutions are designed to improve the scalability, speed, and efficiency of Layer 1 blockchains. Given Celo's unique mobile-first approach and its focus on financial inclusion, I'm curious to know where it fits in this context.