Bonjour,
Essaie comme cela
Sub Traits_CA()
'' Trait plus épais à chaque changement de CA
Dim DerLig As Long, i As Long
With Worksheets("Feuil1")
DerLig = .Range("B" & Rows.Count).End(xlUp).Row
For i = 1 To DerLig
If .Range("B" & i).Value <> .Range("B" & i).Offset(1, 0).Value Then _
.Range("B" & i).EntireRow.Borders(xlEdgeBottom).Weight = xlThick
Next i
End With
End Sub
A+