For each cell in which I enter data on a given day, I'd like the cell's background color to be automatically defined by my computer's system date.

When I go to:

Fill -> Background -> Color -> More Colors

I see an X-Y Color Palette. If I can set the Y coordinate as a function of month, and the x coordinate as a function of day, that would be perfect.

I'd like all cells' background colors to stay constant after data entry, regardless of system date.

Is there any way that I can do this in Excel?

Thank you