You and I think along the same lines.   My first "fix" was the "stack on top"   option.  

However, the powers that be didn't like that - they want the fields side by side, with a better use of the white space.

The fields actually are the the "native" work_notes and comments (as seen by the name of the #id i use in   the CSS Selector) -   we just have changed the text in the labels.    

I just wish ServiceNow would give us better control over layout of forms, the form designer is so limited.     And don't get me started on Catalog forms. It's either a better design tool or move to a flexbox based design so that all this restricted bootstrap control becomes a non-issue.  

I mean   ...   isn't flexbox the the future for Responsive website design? I know it's only at CR stage with W3C, but it will be PR in a fews weeks time and with all the major browsers already supporting it I think it's time SN made the move.