Gray out cells until user makes input

How did they do this??? (attached)

On "Inputs" sheet the user can change the quantity from 0 to any number and then the rest of the table becomes available.
Can someone please describe how this is achieved? There doesn't seem to be any code in the VB editor that makes this happen.

If you don't have a solution on hand could you please tell me what some good google search words would be?

Thank you!

*I had to upload as a zip file because the excel file was slightly greater than 1mb and I wanted to keep everything complete