In that article, " Use Excel's conditional formatting to highlight weekends," we created the sheet shown in Figure A. By separating the year, month, and day, you can reuse the same sheet.

Next, we’ll use a conditional formatting rule to format a cell, based on the combo’ selected value. I’m using (desktop) Office 365 but you can use earlier versions.

Click OK to return to the sheet. Figure F This conditional format will highlight the subtotaling rows. Currently, the data set contains no formulas in column C so there’s no formatting.