Sub CopierCouleur()
On Error Resume Next
If IsError(Workbooks("B.xlsm")) Then MsgBox "Ouvrez 'B.xlsm'": Exit Sub
Application.Goto Workbooks("B.xlsm").Sheets("Feuil2").[B5]
ActiveCell.Interior.Color = ThisWorkbook.Sheets("Feuil1").[C4].DisplayFormat.Interior.Color
End Sub