Create rule for every row, that will highligt a specific duration of time

Hi Guys!
I hope someone can help me out here, as i've puzzled around with this issue for days now, and i just can't make it work.

For some reason, i can't attach the excel file, i've taking a screenshot of the file instead, hopefully that can give you an idea of the task at hand.
The spreadsheet is going to be an overview of date and duration of contracts with clients. As there is going to be several hundreds of clients, i want excel to make an automatic code, for highlightning the duration dates of the contracts.
I've done this with conditional formatting in the spreadsheet with one of the rows. And this is what i want excel automatically do for the coming rows. Does it make sense? I hope so.

If any kind person, would give their input of any relevance, it would be so greatly appreciated.

Kind regards.
Nico