I've figured out how to create the illusion of a table inside a collection in modern designer. I've used Field Rules, Lookup Rules and hidden fields with formulas to create the illusion of a table inside the collection.

In reality each 'table row' is another collection item of fields with the other fields hidden. 

The result is this. I'd like to add a combo of JS and CSS to remove the field labels on those additional rows. There's a hidden field called 'IS ADDITIONAL ROW', and when it's 'TRUE' it turns on the Field Rules that create the illusion of a table in a collection. 

I'd also like JS/CSS to hide the field labels at the same time.