excel if/then functions with dates and colour

Hello, this will be mine first post on this forum, and I think not the last one.

The following is driving me crazy.
I have a spreadsheet that shows the planning and availability of demo systems for a whole year.
There is a start date (cell A2) and an end date (cell B2) that I manual type in.
In Row 1 from cell C1 - IV1) I have all the dates of one year.
If I fill out the dates I colour the cells in the row manual.

Now I am looking for a formula that colours these cells automatic when I type in the dates.

Thanks.

Prins