How to customize Combobox dropdown List background (trasparet and make it rounded if posible) in delphi 11.3 FMX

I am tring to make a rounded combobox and a the dropdown trasparent (and rounded if posibole )

and so far all i can thik of is that i can put it inside a rectangel and edit the background style of the combobox to trasparent but ... the dropdown List Background is not trasparent and from what i read from this Post https://blog.andreamagni.eu/2021/11/customizing-tcombobox-dropdown-in-fmx/ it's bien handel by another style of Listbox i tried what he said in the post but it's not working so is there anythin that i am missing or it's a dephi vertion problem (I am using the latest vertion of delphi 11.3 in FMX fram work)

It still works fine for me, see the attached screenshots. You're missing the combopopupstyle part. Here is the content of a .style file:

object TStyleContainer
  object TRectangle
    StyleName = 'ListBoxstyle'
    Align = Center
    Fill.Color = x3060BBFF
    HitTest = False
    Margins.Bottom = 2.000000000000000000
    Size.Width = 200.000000000000000000
    Size.Height = 200.000000000000000000
    Size.PlatformDefault = False
    Stroke.Kind = None
    Stroke.Thickness = 0.000000000000000000
    Visible = False
    XRadius = 12.500000000000000000
    YRadius = 12.500000000000000000
    object TScrollBar
      StyleName = 'vscrollbar'
      Align = Right
      SmallChange = 0.000000000000000000
      Orientation = Vertical
      Margins.Top = 7.000000000000000000
      Margins.Right = 3.000000000000000000
      Margins.Bottom = 7.000000000000000000
      Position.X = 189.000000000000000000
      Position.Y = 7.000000000000000000
      Size.Width = 8.000000000000000000
      Size.Height = 186.000000000000000000
      Size.PlatformDefault = False
      StyleLookup = 'ListBoxstyleScrollBarStyle'
      TabOrder = 1
    end
    object TLayout
      StyleName = 'content'
      Align = Client
      ClipChildren = True
      Margins.Left = 3.000000000000000000
      Margins.Top = 3.000000000000000000
      Margins.Right = 4.000000000000000000
      Margins.Bottom = 3.000000000000000000
      Size.Width = 182.000000000000000000
      Size.Height = 194.000000000000000000
      Size.PlatformDefault = False
      TabOrder = 2
      object TRoundRect
        StyleName = 'selection'
        Fill.Color = x40AAAAFF
        HitTest = False
        Size.Width = 50.000000000000000000
        Size.Height = 50.000000000000000000
        Size.PlatformDefault = False
        Stroke.Kind = None
      end
    end
  end
  object TRoundRect
    StyleName = 'ComboBoxStyle'
    Align = Center
    Fill.Color = x60000000
    HitTest = False
    Size.Width = 150.000000000000000000
    Size.Height = 24.000000000000000000
    Size.PlatformDefault = False
    Stroke.Kind = None
    Stroke.Thickness = 0.000000000000000000
    Visible = False
    object TPath
      StyleName = 'arrow'
      Align = Right
      Data.Path = {
        26000000000000007F0A8D43A2059942010000006DE78543B7F3784202000000
        F8F38443F95371420200000086DB83432C876D4202000000779E82432C876D42
        020000002D6281432C876D4202000000DB498043F953714202000000CDAC7E43
        B7F37842010000004C770E43E5702E43010000009318F241C9F6784202000000
        3BDFE2410B577142020000001C5AD1413E8A6D42020000005C8FBD413E8A6D42
        020000008FC2A9413E8A6D4202000000703D98410B5771420200000025068941
        C9F6784201000000B4C83640AE079942020000003333733F81D59C4202000000
        00000000C936A1420200000000000000FC29A6420200000000000000291CAB42
        02000000CFF7733F717DAF4202000000B4C83640444BB3420100000025E60743
        69B15E43020000000ECD09439498604302000000F4FD0B43098C614302000000
        4C770E43098C614302000000A4F01043098C6143020000008320134394986043
        020000002B07154369B15E43010000007F0A8D43444BB34202000000F4FD8D43
        EE7CAF4202000000E9768E43A61BAB4202000000E9768E43FC29A64202000000
        E9768E43C936A14202000000F4FD8D4381D59C42020000007F0A8D43A2059942
        030000007F0A8D43A2059942}
      Fill.Color = claWhite
      HitTest = False
      Margins.Top = 9.000000000000000000
      Margins.Right = 9.000000000000000000
      Margins.Bottom = 9.000000000000000000
      Position.X = 131.000000000000000000
      Position.Y = 9.000000000000000000
      Size.Width = 10.000000000000000000
      Size.Height = 6.000000000000000000
      Size.PlatformDefault = False
      Stroke.Color = claNull
      Stroke.Thickness = 0.000000000000000000
      WrapMode = Fit
    end
    object TLayout
      StyleName = 'content'
      Align = Client
      Locked = True
      Margins.Left = 3.000000000000000000
      Margins.Top = 3.000000000000000000
      Margins.Bottom = 3.000000000000000000
      Size.Width = 128.000000000000000000
      Size.Height = 18.000000000000000000
      Size.PlatformDefault = False
      TabOrder = 1
    end
  end
  object TLayout
    StyleName = 'combopopupstyle'
    Align = Center
    Size.Width = 50.000000000000000000
    Size.Height = 50.000000000000000000
    Size.PlatformDefault = False
    Visible = False
    TabOrder = 12
  end
  object TLayout
    StyleName = 'ListBoxItemstyle'
    Align = Center
    Size.Width = 150.000000000000000000
    Size.Height = 24.000000000000000000
    Size.PlatformDefault = False
    Visible = False
    TabOrder = 16
    object TActiveStyleTextObject
      StyleName = 'text'
      Align = Client
      Margins.Left = 8.000000000000000000
      Margins.Top = 1.000000000000000000
      Margins.Right = 8.000000000000000000
      Margins.Bottom = 1.000000000000000000
      Size.Width = 134.000000000000000000
      Size.Height = 22.000000000000000000
      Size.PlatformDefault = False
      Text = 'Text'
      TextSettings.WordWrap = False
      TextSettings.HorzAlign = Leading
      ShadowVisible = False
      ActiveTrigger = Selected
      ActiveColor = claBlack
    end
  end
  object TLayout
    StyleName = 'ListBoxstyleScrollBarStyle'
    Align = Center
    Size.Width = 200.000000000000000000
    Size.Height = 200.000000000000000000
    Size.PlatformDefault = False
    Visible = False
    TabOrder = 3
    object TTrack
      StyleName = 'vtrack'
      Align = Client
      Locked = True
      Orientation = Horizontal
      Margins.Left = 1.000000000000000000
      Size.Width = 199.000000000000000000
      Size.Height = 200.000000000000000000
      Size.PlatformDefault = False
      StyleLookup = 'vscrollbarscrollbarvtrackstyle'
    end
  end
  object TRoundRect
    StyleName = 'vscrollbarscrollbarvtrackstyle'
    Align = Center
    Fill.Color = x15000000
    HitTest = False
    Size.Width = 6.000000000000000000
    Size.Height = 316.000000000000000000
    Size.PlatformDefault = False
    Stroke.Kind = None
    Stroke.Thickness = 0.000000000000000000
    Visible = False
    object TThumb
      StyleName = 'thumb'
      Locked = True
      Size.Width = 6.000000000000000000
      Size.Height = 50.000000000000000000
      Size.PlatformDefault = False
      TabOrder = 0
      object TRoundRect
        StyleName = 'scrollthumb'
        Align = Contents
        Fill.Color = x30000000
        HitTest = False
        Size.Width = 6.000000000000000000
        Size.Height = 50.000000000000000000
        Size.PlatformDefault = False
        Stroke.Kind = None
        Stroke.Thickness = 0.000000000000000000
      end
    end
  end
end