Elon Musk is serious about getting his Twitter staff to adopt a “hardcore” attitude at work. San Francisco’s Department of Building Inspection said it is investigating a complaint that the company has set up makeshift bedrooms at its corporate headquarters in the city in violation of zoning practices. Mr. Musk sent out a tweet attacking the city and its mayor London Breed. “So city of SF attacks companies providing beds for tired employees instead of making sure kids are safe from fentanyl. Where are your priorities @LondonBreed!?”