Simple Front-End Browser-Based Javascript Web Page for Question Answering

I want a very simple app similar (but more elegant) in looks to the one found on this link: https://storage.googleapis.com/tfjs-models/demos/mobilebert-qna/index.html
There is an existing javascript code from github (which I already tested) to be used to create this app… See my test app through the link below (use the console to view the results):
https://codepen.io/kingsleysunday/pen/vYXRxZg

Deliverables:
1. html, javascript and css files if possible
2. Ability to upload a text file or pdf file to be processed on the browser (no server-side processing)
3. Ability to copy and paste the text into the input bar
4. Results should be easily generated on screen (as shown in my codepen example)
5. A strong candidate would be one who can make the text of the answer area highlighted on screen within the passage.

Feel free to ask any questions you have.