Private Sub Worksheet_Activate()
    Dim sh As Worksheet, arr(), lr As Long, i As Long, ii As Long
    Application.ScreenUpdating = False
    lr = Cells(Rows.Count, "B").End(xlUp).Row
    arr() = Range("B1").Resize(lr).Value
    Range("B11:B" & lr).Interior.ColorIndex = xlColorIndexNone
    For i = 11 To UBound(arr)
        For ii = 2 To Worksheets.Count
            Set sh = Worksheets(ii)
            lr = sh.Cells(sh.Rows.Count, "C").End(xlUp).Row
            If lr > 15 Then
                If WorksheetFunction.CountIf(sh.Range("C16:C" & lr), arr(i, 1)) <> 0 Then
                    Cells(i, "B").Interior.Color = 8696052
                End If
            End If
        Next ii
    Next i
    Application.ScreenUpdating = True
End Sub