Visualization - Matrix - change background color based upon specifc columns

Assume your value measure is:

[Sales] = SUM(Fact[Sales])

Create a rank measure (ranks products within the current Store column):

Rank in Store =
RANKX(
    ALLSELECTED(Products[Product]),
    [Sales],
    ,
    DESC,
    Dense
)

Now create a color measure:

Top 3 Color =
VAR r = [Rank in Store]
RETURN
SWITCH(
    TRUE(),
    r = 1, "#C6EFCE",   -- green
    r = 2, "#FFEB9C",   -- yellow
    r = 3, "#F8CBAD",   -- red
    BLANK()
)

Apply it:

• Select the Matrix

• In the Values field dropdown (the measure you’re coloring) → Conditional formatting → Background color

• Format by: Field value

• Based on field: [Top 3 Color]

or as a measure