Help going to ikea live : White or Wood board on the drawer unit

I want to put a board on top of the drawer unit so it goes to the wall and makes my desk bigger

I don't know if i should take a white board, so it fits the white the unit drawer and the end of my desk

Or if I should take the same color as my desk (it's gonna be identical, as i'll take it as ikea as well)

Note that the computer won't stay there

Thankssss🩷