Update the demo

[AdamSalma]

Hi, the demo looks weak compared to this repo's potential... (speaking as a former user from v2.4.0)

As a first-point contact with this library you'd expect the demo to shine the most, perhaps even have a full-sized page to play around with, instead of a small screen in a code playground. Black as the default theme? What business is going to be thrilled by seeing that?

This is just personal opinion, do with it what you will + best of luck.

[nelsonf94]

I think so too.