AbbyPi.

It does work.

To get the concept just forget about merge fields for a minute.

1. Create a 1 row x 2 column table.
2. Set the cell margins right, left, top and bottom to 0 pts.
3. Create a simple conditional IF field as shown.
4. Format the "I" in "IF" with yellow highlight
5. Insert a right aligned tab space just passed the right border of cell 1.

2019-04-19_17-11-00.jpg

6. Select all, update fields and toggle field codes.
7. Since the condition is met, the entire content of the cell will be highlighted yellow.
8. Toggle fields codes, change 1 = 1 to 1 = 2. Repeat select, update toggle and the highlighting goes away.