Conditional Formatting for Borders

Here is a good one for all my helpers from all over the world. Attached is another project I have on my Sudoku game. This one is called Loco Sudoku and there are no 3x3 grids. These 3x3 grids are still there but they have taken on a new shape as you will see on the attached, and each one is surrounded by a border and each has it's own color, so since you'all are familiar with highlighting columns/rows you know that the conditional formatting for highlighting columns/rows has rule over any color already placed in a cell, so wondering if it is possible to highlight just the borders of cells and therefore the cells colors would not change. The reason for this is that in this version of the game you need to keep track of the number because of the way they are placed on the sheet. On the attached you will need to turn on the highlighter. The one who solves this gets a free copy of the puzzle (LOL) and it is fun to play.

Thanks

Never mind, doesn't seem like a good ideal to do this.