Please only make a topic once. I have approved this copy, but had rejected (and deleted) your other topic in a different category.
About your question:
Not behind my work laptop right now, so I can't test this, but I am thinking along the lines of something like this:
if(SomeExpression > above(SomeExpression, ARGB(50,255,0,0), ARGB(50,0,255,0))
Put that thing in the background color box.
Of course replace "SomeExpression" by the actual expression you are using.