Code help for excel

So, I have a an issue that is more advanced then I am. The premise is that in cell D16 a date is entered, in E16 a WORKDAY function is used, =if({@column6}="","",WORKDAY(D16,10)) to count the deadline date. This works great. But what I want to do is have conditional formatting of E16 change colors, green, orange, and red, as time gets closer to the shown E16 date. Also, sometimes E16 will be over written to have a sooner deadline but I still want the conditional formatting to work.

 

Thoughts?

 

Thanks, Craig