Code Works in codepen. Doesn't work in website. Calculator Code

So I very new to code, I managed to write out some code to control a calculator form for a client.

Here is my codepen link:
The code works perfectly with the basic HTML in codepen. However, I am probably missing something because I cannot for the life of me implement the code into my webflow page. I have added an embed in my webflow form, I have tried the code in the page settings body code. Nothing seems to work. I made use that the ID tags for the items should match my code.

I don’t know what the issue is so its hard to research a fix.

Here is my site Read-Only: Webflow - Atlas Industries Inc