Sub Bouton2_QuandClic()
Dim j As Byte, couleur As Byte
Dim i As Integer
For j = 1 To Range('iv1').End(xlToLeft).Column
For i = 1 To Cells(65536, j).End(xlUp).Row 'To 1 Step -1
Select Case i
Case Cells(65536, j).End(xlUp).Row: couleur = 3 'derniere ligne
Case Cells(65536, j).End(xlUp).Row - 1: couleur = 44 'avant derniere
Case Else: couleur = 43 'les autres
End Select
Cells(i, j).Interior.ColorIndex = couleur
Next i
Next j
End Sub