Copy conditional formatting with relative data

Hello,

I'm hoping someone here can help me out...

See attachment.
If 'time used' is >= 'time available', the cell 'time used' has to be colored red
If 'time used' is 0, the cell 'time used' has to be colored green
Everything in between 0 and 'time available' has to be colored between green and red (yellow, orange,…)

I’m able to do this cell by cell but it seems to be impossible to copy the conditional formatting to other cells because it always seems to refer to A2 instead of A3, A4,…

I have more than 200 lines like this so manual would take ages.

Can someone maybe tell me how to do this?

Thanks a lot in advance!

Sophie