Help formatting Matrix row subtotals in desktop

Hello,

I have a matrix where I'm being asked to highlight the subtotaled rows for the visualization. By changing the settings in Row Subtotals I'm able to highlight the rows, however it stops short at the Grand totals column. Is there a way to extend that highlight all the way across the matrix?

Adjusting the background via Column Grand total just highlights the entire columns. 

I feel like it's probably simple but I've been stumped on this all morning. 

Any help would be greatly appreciated!