I am trying to set up a spreadsheet that is at this present moment in time
getting the better of me. I know what I want it to do, but cant seem to get
it to do it.

What I want it to do is to highlight the cell red, amber or green to
indicate how close we are to our deadline date.

For example: I have three columns: Date In, Deadline Date and Todays Date.
What I want to happen is for the Deadline Date column to highlight
automatically each day as we count down to the Deadline Date. I dont really
want to have to be going in to the spreadsheet every day to manually change
the dates but I have no idea how to get it to update automatically. Any
suggestions?