Javascript function for game sensitivity converter is not working on my web

I am a final year highschool. For my project, we decided to make front-end css for our game sensitivity converter website.

I have copied code from this website https://sensitivityconverter.com/

But on jsfiddle, my code is not working. I can see the form but I couldn’t figure out how to make the calculation works like on original website.

https://jsfiddle.net/60jyo4hz/ enter code here

Please forgive me for my poor grammar.