using Conditional formatting

Select A1 and then enter these 3 new rules with "Use a formula ...." option

for 1. =AND(A2="",A3="") Set FILL to RED

for 2: =OR(AND(A2="",A3="x"),AND(A2="x",A3="")) set FILL to orange

For 3: =AND(A2="x",A3="x") set FILL to GREEN