"T. Valko" wrote...
....
Alternatives:

If the cell contains a number from 1 to 12 one or the other formats is
applied.
....

Good point.

blue: =IF(ISTEXT($AK$2),MOD(MONTH($AK$2&"-1"),2)=1)

green: =IF(ISTEXT($AK$2),MOD(MONTH($AK$2&"-1"),2)=0)

These allow whitespace in AK2. If that's not OK, then change the
second cell
references to SUBSTITUTE($AK$2," ","%").