Dark and Light Grey, Red and Green

I finally understand what that little graph is about. The dark grey bars are the amount of words I have to write every day in order to make the target, assuming I write the same number of words every day. If I don't meet the target, then I get a green portion for how much I wrote, and a red portion for how much I fell short. If I exceed my target, the excess is green and the required amount is light grey. That much is obvious.

What's really clever, is that it's dynamic. As I fall behind on my targets, the amount I have to write each day obviously increases, and the dark grey bars increase in length to reflect this. At the moment I need 2000 words a day to meet my target. Hopefully that should come down a bit, as I'm planning to attempt a little writing binge over the next couple of days...