formating according to how far away a value is from ideal value

[itge13]

Formating according to how far away a value is from an ideal value. E.g. ideal value is 100, the lowest value 10 should become dark red, 20 ligther red, 30 maybe orange etc. the nearer it gets to the ideal value the greener (or less red or whatever) it becomes. The same for the other direction for numbers over 100.