Colorization of entire field background within a row

This is a simple result of the CSS Box Model. With a formula you can control the styling of the content of the cell (ie <td>content</td>) but you can't control the styling of the cell itself.  (ie <td style='...'>)

To gain control of the styling of the cell you have to use script. It is an easy fix with script but you probably have to have some logic or convention as to which cells need the special styling as you probably don't want to apply it to every cell in the report.