Simple but it works.
Code
Sub ToggleColor()
Dim StartRow, iRow, EndColumn As Integer
Dim ShadeColor, UseColor As Single
Dim ShadeOn As Boolean
StartRow = 3
EndColumn = 25
'ShadeColor = -0.05 'lighter
ShadeColor = -0.15 'medium
'ShadeColor = -0.25 'darker
ShadeOn = False
iRow = StartRow
Do
If Cells(iRow, 3) <> Cells(iRow - 1, 3) Then
If ShadeOn Then
ShadeOn = False
UseColor = 0#
Else
ShadeOn = True
UseColor = ShadeColor
End If
End If
ActiveSheet.Range(Cells(iRow, 1), Cells(iRow, EndColumn)).Select
With Selection.Interior
.Pattern = xlNone
.PatternColorIndex = xlAutomatic
.ThemeColor = xlThemeColorDark1
.TintAndShade = UseColor
.PatternTintAndShade = 0
End With
iRow = iRow + 1
Loop While Cells(iRow, 3) > ""
End Sub
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