Private Sub Worksheet_Activate()
Dim i As Integer
Dim dernière_colonne As Integer
dernière_colonne = 1
While Cells(3, dernière_colonne) <> ""
dernière_colonne = dernière_colonne + 1
Wend
For i = 1 To dernière_colonne
If Cells(2, i) > "" Then
Range(Cells(2, i), Cells(3, i)).Borders(xlEdgeLeft).Weight = xlMedium
End If
Next i
End Sub