Bonjour,
A titre de test pour une substitution ...
Sub TestLigne()
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Dim i As Long
Dim der As Long
der = ActiveSheet.Cells(Rows.Count, "A").End(xlUp).Row
For i = 3 To der
If Cells(i, 1) <> Cells(i - 1, 1) Then Range("A" & i & ":" & "F" & i).Borders(xlEdgeTop).LineStyle = xlContinuous
Next i
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
End Sub
En espèrant que cela t'aide