Date Conditional formatting

Try the following code:

Conditional Colour = 
VAR temptable =
    TOPN ( 1, 'Table', 'Table'[Last Sale Date], ASC )
VAR DateSelection =
    MAXX ( temptable, 'Table'[Last Sale Date] )
RETURN
    SWITCH (
        TRUE (),
        COUNTROWS(temptable) = 0 , BLANK(),
        DateSelection= BLANK (), "Black",
        DATEDIFF ( DateSelection, TODAY (), MONTH ) < 1, "Green",
        DATEDIFF ( DateSelection, TODAY (), MONTH ) < 3, "Light Blue",
        "Red"
    )

No use the condittional formatting from field value:

Hi RDF25087 ,

My bad, should be less than or equal to 1 redo the measure to:

Conditional Colour = 
VAR temptable =
    TOPN ( 1, 'Table', 'Table'[Last Sale Date], DESC)
VAR DateSelection =
    MAXX ( temptable, 'Table'[Last Sale Date] )
RETURN
    SWITCH (
        TRUE (),
        COUNTROWS(temptable) = 0 , BLANK(),
        DateSelection= BLANK (), "Black",
        DATEDIFF ( DateSelection, TODAY (), MONTH ) <= 1, "Green",
        DATEDIFF ( DateSelection, TODAY (), MONTH ) <= 3, "Blue",
        "Red"
    )

Since the calculation is in months values above 0.5 round to 1and were not considered. You may need to make some more adjustments using rounding or similar but believe this may be enough: