How to format a column with negative percentage numbers in RED

I would appreciate some guidance on how to format a column to showing "percentages" with negative numbers in RED.

This is the basic formular I use to calculate the percentages.  =IF(B4=0," ",+(B4/C4)-1), =IF(B5=0," ",+(B5/C5)-1), etc... as below.  The column Format Cells is set for Percentage.  I would like any negative percentage values in the column to be shown in RED.

Thank you, Steve