Private Sub Worksheet_Activate()
Dim Sh As Worksheet, Li As Byte, Col As Byte, N As Byte, C As Range
Application.ScreenUpdating = False
[C5:AL38].Interior.ColorIndex = xlNone
For Each Sh In Worksheets
If Left(Sh.Name, 1) = "Trimestre" Then 'pour chaque feuille T...
N = Val(Right(Sh.Name, 1)) - 1 'numéro onglet pour colonnes
For Li = 5 To 33 'pour chaque ligne
For Col = 1 To 26 ' pour chaque colonne
If Sh.Cells(Li, Col).Interior.ColorIndex <> xlNone Then
For Each C In Range("C2:AL2")
If C = Sh.Cells(2, Col) Then Cells(Li, C.Column + N).Interior.Color = Sh.Cells(Li, Col).Interior.Color
Next
End If
Next
Next
End If
Next
End Sub