It’s easy to do side navigation with flexbox.
It is enough to make a block with the nav class a flex container and distribute the elements in it with a bell.
Another thing to add is a width, say 150px.
For the body element, give a margin of 0px.

This task is part of the Full-Stack JavaScript Course .
If you have any issues with it, you can ask for community help below the post.
Feel free to help others if you’ve already solved the task.

index.html

<!DOCTYPE html>
<html>
  <head>
    <title>Side navigation</title>
  </head>
  <body>
    <div class="nav">
      <a href="https://js.coderslang.com/navigation/217" class="nav-item">
        JS Coderslang
      </a>
      <a href="https://play.google.com/store/apps/details?id=com.coderslang.com&hl=en&gl=US" class="nav-item">
        Android App
      </a>
      <a href="https://apps.apple.com/us/app/coderslang-learn-programming/id1489105103" class="nav-item">
        iOs App
      </a>
    </div>
  </body>
</html>