White background hurts eyes a lot. As an application that the developer community uses 8+ hours per day, you should be more responsible and implement dark/night theme immediately. 

As you may see in here https://twitter.com/SlackHQ/status/895301561961918468, this request has a high demand for more than 2+ years. 

Please show that you care about the community and you listen to such a request that may improve our health quality.