Update Demo Page to Include More Use Cases

I think demo page should have more features so potential users can see what Nightowl can do in a real-world scenario.
It should also address some of the issues it currently has like box-shadow and position: fixed to name a few, so when they're fixed, it would be perceived in the demo page.

I currently did some work on my forked branch and it's 80% done.
If it's OK, I'll want to make a pull request when it's complete.