title: Why did the classes from libraries I imported is showing in red colour? I could build it perfectly and run works fine
body: <p>This is my app project. The classes looks fine</p>
  <p><a href="https://i.stack.imgur.com/oKrO9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oKrO9.png" alt="" /></a></p>
  <p>This is the libraries I imported as module. The classes are red in colour, why?</p>
  <p><a href="https://i.stack.imgur.com/MNPcJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MNPcJ.png" alt="" /></a></p>